3. substitution of Co with Fe. The experimental proce
dures as well as the major results and findings are
next presented and discussed.
2. Experimental procedure
Five WC-(Co+Fe+Ni) cemented carbides were fabri
cated using commercially available powders of WC
(d50 ~ 10 µm, 98.5% purity; Goodfellow), Co (d50
~ 1.6 µm, 99.8% purity; Alfa Aesar), Fe (d50 ~ 3 µm,
99.8% purity; Sigma Aldrich), and Ni (d50 ~ 5 µm, 99%
purity; Sulzer Metco). They were all designed to have
90 wt.% WC and 2 wt.% Ni, but different Fe/Co ratios as
listed in Table 1. First of all, the Co, Fe, and Ni powders
were ball milled (Turbula T2 F Shaker-Mixer) in dry
conditions in appropriate relative concentrations at
room temperature under Ar atmosphere for 1 h,
using stainless steel balls, a ball-to-powder weight
ratio of 5:1, and a rotation speed of the stainless steel
container of 150 rpm. The resulting Co-Fe-Ni alloys
were then mixed with the WC powder, and ball milled
at room temperature under Ar atmosphere for 2 h.
Stainless steel balls (of 10 mm diameter) and container
as well as 150 rpm were used again, but the ball-to-
powder weight ratio was 10:1. The resulting powder
mixtures were next uniaxially pressed into cylindrical
pellets under 150 MPa pressure for 4 min, which were
subsequently pressureless sintered (Carbolite Gero) in
stationery Ar atmosphere. The sintering cycle involved
heating to 580°C at 6°C/min and soaking there for 1 h,
then heating to 1200°C at 5°C/min and soaking there
for 1 h, next heating to the sintering temperature of
1400°C at 4°C/min and soaking there for 1 h, and finally
cooling to room temperature at 6°C/min.
The sintered WC-10 wt.%(Co+Fe+Ni) cemented car
bides were first ground with SiC sandpapers (up to
2000 mesh) and then polished with diamond suspen
sions up to a 1-µm finish, and were characterized
microstructurally, mechanically, and tribologically.
Specifically, the microstructural characterization was
performed by optical microscopy (Nikon Eclipse LV
100 ND), scanning electron microscopy (SEM; JOEL
JSM 6063) coupled with energy-dispersive X-ray spec
troscopy (EDS; EDAX), densitometry immersion
(Archimedes principle), and X-ray diffractometry (XRD;
Panalytical X’pert Pro). The SEM images were acquired
at 19 keV, using backscattered electrons. The XRD
patterns were measured with incident radiation Cu-
Kα, in the angular interval 30–80 º2θ with step of 0.02
º2θ. The hardness (HV10) was determined from 10
replicate measurements (Model FV-700, Future-Tech
Corp.) in accordance with ASTM E92-17 (2017b) using
an indentation load of 10 kgf and a dwell time of 10
s. Finally, the tribological performance was evaluated
by dry sliding tests (i.e., without lubricant) under the
pin-on-disk geometry (Tribometer CSM, CSM
Instruments Inc.) as per the ASTM G99-17 standard
[21]. Disks of the WC-10 wt.%(Co+Fe+Ni) cemented
carbides with 2 cm diameter and 3 mm thickness
were utilized, which were weighted with an accuracy
of 0.1 mg prior to wear testing. Al2O3 balls of 6 mm
diameter were used as counterpart (hardness of 60
HRC), rotated at normal loads (F) of 10, 15, or 20 N on
the surface of the WC-10 wt.%(Co+Fe+Ni) cemented
carbides at a linear sliding speed of 15 cm/s under
a track radius of 3 mm for a total sliding distance (d)
of 2000 m. The coefficients of friction were continu
ously logged during the tribological tests, and the
wear rates were calculated by standard procedures
and equations from the mass loss accumulated at the
end of the tribological tests [22]. To this end, the WC-
10 wt.%(Co+Fe+Ni) disks were first cleaned with acet
one and then re-weighted, next evaluating the specific
wear rates (SWRs; mm3
/(Nm)) by the following expres
sion [23]:
SWRs ¼
Δm
ρdF
where Δm is the mass loss, ρ the density, and d and
F have been defined before.
Lastly, the worn surfaces were also characterized by
SEM/EDS to shed light on the wear damage and
modes/mechanisms. Again, the SEM images were
acquired at 19 keV, using backscattered electrons.
3. Results and discussion
Figure 1 shows SEM micrographs of the five WC-10 wt.
%(Co+Fe+Ni) cemented carbides sintered with differ
ent Fe/Co ratios. It can be seen that they are all formed
by WC grains (lighter phase) homogeneously distribu
ted together with a metal binder (darker phase), and
that their microstructures are relatively coarse because
the average particle size of the WC starting powder is
as large as ~10 µm. A subtle microstructural difference
between these cemented carbides is, however, that
the contiguity data of the WC phase presented in
Table 2 indicate that the carbide skeleton developed
during sintering becomes more continuous as the Fe/
Co ratio increases. Importantly, as also seen in Table 2,
the direct density measurements performed by the
Archimedes method indicated that these cemented
carbides are all essentially dense, with absolute densi
ties in the range 13.39–13.76 g/cm3
and porosities of
Table 1. Designation and composition of the five WC-10 wt.%
(Co+Fe+Ni) cemented carbides fabricated by pressureless sin
tering at 1400°C.
Designation
Composition (wt.%)
Fe/Co ratio
WC Co Fe Ni
WC-(8 wt.%Co+2 wt.%Ni) 90 8 0 2 Without Fe
WC-(6 wt.%Co+2 wt.%Fe+2 wt.%Ni) 90 6 2 2 1/3
WC-(4 wt.%Co+4 wt.%Fe+2 wt.%Ni) 90 4 4 2 1
WC-(2 wt.%Co+6 wt.%Fe+2 wt.%Ni) 90 2 6 2 3
WC-(8 wt.%Fe+2 wt.%Ni) 90 0 8 2 Without Co
2 F. DJEMATENE ET AL.
4. only ~1%. Nonetheless, the absolute density increased
slightly and the residual porosity decreased slightly
with increasing Fe/Co ratio to 1 (WC-(4 wt.%Co+4 wt.
%Fe+2 wt.%Ni)), above which both trends reversed as
the Fe/Co ratio continued to increase. These complex
trends are attributable to Fe addition on the one hand
lowering the temperature for liquid formation [16], but
on the other hand also lowering the wettability of the
WC grain in the liquid phase [24,25].
Figure 2 shows the XRD patterns of the five WC-
10 wt.%(Co+Fe+Ni) cemented carbides sintered with
different Fe/Co ratios. It is clear that they all contain WC
as main phase, plus minor concentrations of the car
bide W2C and of the corresponding metals (Co, Fe, and
Ni). Thus, the only difference is that the progressive
substitution of Co by Fe eventually resulted in the
greater formation of the ternary carbide Fe3W3C (M6C
phase), at the expense of the reduction of the W2C
content via the chemical reaction 3 Fe+3/2 W2C→Fe3
W3C + 1/2 C [26].
Figure 1. SEM micrographs of the five WC-10 wt.%(Co+Fe+Ni) cemented carbides fabricated by pressureless sintering at 1400°C
with equal Ni content (2 wt.%) but different Fe/Co ratios: (a) Fe = 0, (b) Fe/Co = 1/3, (c) Fe/Co = 1, (d) Fe/Co = 3, and (e) Co = 0.
Table 2. Properties of the five WC-10 wt.%(Co+Fe+Ni) cemen
ted carbides pressureless sintered with different Fe/Co ratios.
Fe/Co ratio
WC
contiguity
Absolute density
(g/cm3
)
Porosity
(%)
Hardness
(kg/mm2
)
Without Fe 0.31 13.39 0.96 980
1/3 0.40 13.43 0.81 1015
1 0.43 13.76 0.77 1090
3 0.44 13.62 0.85 1045
Without Co 0.46 13.36 1.12 965
Figure 2. XRD patterns of the five WC-10 wt.%(Co+Fe+Ni)
cemented carbides pressureless sintered with different Fe/Co
ratios, as indicated. Representative XRD peaks of the crystal
line phases identified are marked with symbols.
JOURNAL OF ASIAN CERAMIC SOCIETIES 3
5. Table 2 also gives the HV10 values measured by
Vickers indentation for the five WC-10 wt.%(Co+Fe
+Ni) cemented carbides sintered with different Fe/Co
ratios. It is seen that HV10 varies in the range
965–1090 kg/mm2
, with the hardest cemented carbide
(WC-(4 wt.%Co+4 wt.%Fe+2 wt.%Ni)) having a hard
ness of ~1090 kg/mm2
. These are typical hardness
values for WC-based cemented carbides with 10 wt.%
metal binder. Nonetheless, it can also be seen in Table
2 that the hardness of these cemented carbides
depends on their Fe/Co ratio. In particular, it is
observed that hardness first increased with increasing
Fe/Co ratio up to 1 (WC-(4 wt.%Co+4 wt.%Fe+2 wt.%
Ni)), above which it decreased as the Fe/Co ratio con
tinued to increase. This is the inverse of the trend
exhibited by the residual porosity, which is therefore
the key factor determining the hardness. This is espe
cially notable because Co is harder than Fe, and thus
according to compositional considerations these
cemented carbides should have been increasingly
softer as the Fe content increased, which was not the
case. Moreover, one also notes for example that,
despite the cemented carbide sintered without Co
(WC-(8 wt.%Fe+2 wt.%Ni)) containing the highest con
centration of the hard M6C phase in its microstructure,
it is the softest of the five cemented carbides because
it is also the most porous of them. In conclusion, subtle
differences in residual porosity had an important
impact on the hardness of these cemented carbides.
As for the wear behavior, Figure 3 shows by way of
example the curves of coefficient of friction logged
during the tribological tests at 20 N (the highest load
applied) for the five WC-10 wt.%(Co+Fe+Ni) cemented
carbides sintered with different Fe/Co ratios. It can be
seen that in general there is initially a running-in stage
during the first 100 m of sliding in which the coefficient
of friction increases as the rotating counter-ball
progressively polishes the contact surface of the corre
sponding cemented carbide, and that there is then
a steady-state stage during the rest of the tribological
test in which the coefficient of friction remains stable
once plowing has smoothed the wear track surface.
The cemented carbide sintered without Co (WC-(8 wt.
%Fe+2 wt.%Ni)) is an exception, however, with the
coefficient of friction gradually increasing up to large
sliding distances (~1500 m), and then flattening out.
This reflects that, in this particular case, the roughness
of the contact surface increased during most of the
tribological test, and then stayed at that condition.
More importantly, it can also be seen that the Fe/Co
ratio in these cemented carbides affected the steady-
state coefficient of friction, which first decreased with
increasing Fe/Co ratio up to 1 (WC-(4 wt.%Co+4 wt.%
Fe+2 wt.%Ni)) and then increased with further increase
of the Fe/Co ratio. This same trend also applies for the
coefficients of friction measured during the tribologi
cal tests performed at 15 and 10 N, in which these
coefficients gradually declined with decreasing applied
load. Thus, regardless of the applied load, the steady-
stage coefficients of friction follow the reverse trend
with the Fe/Co ratio observed for the hardness, and
then the same trend as observed for the residual
porosity.
With regard to the wear resistance, Figure 4 shows
the SWRs calculated at the end of the tribological tests
for the five WC-10 wt.%(Co+Fe+Ni) cemented carbides
sintered with different Fe/Co ratios. There are two
relevant observations to be mentioned. Firstly, regard
less of the Fe/Co ratio in these cemented carbides, the
SWRs increased with increasing applied load. Secondly,
and more importantly, regardless of the applied load,
the SWRs first decreased with increasing Fe/Co ratio up
to 1 (WC-(4 wt.%Co+4 wt.%Fe+2 wt.%Ni)), and then
increased with further increase of the Fe/Co ratio. It is
Figure 3. Friction curves (coefficient of friction vs sliding dis
tance) registered during the tribological tests at 20 N for the
five WC-10 wt.%(Co+Fe+Ni) cemented carbides pressureless
sintered with different Fe/Co ratios, as indicated.
Figure 4. Specific wear rates determined from the mass losses
at the conclusion of the tribological tests at 10, 15, and 20 N
for the five WC-10 wt.%(Co+Fe+Ni) cemented carbides pres
sureless sintered with different Fe/Co ratios, as indicated.
4 F. DJEMATENE ET AL.
6. thus evident that the SWRs correlate inversely with the
hardness of these cemented carbides, and then
directly with their residual porosities. By way of exam
ple, these two correlations are illustrated in Figure 5 for
the tribological tests performed at 20 N. The correla
tion is not linear, however, because there are other
minor factors affecting the wear resistance. In any
case, it is also worth noting that the SWRs are all of
the order of magnitude of just 10−6
mm3
/(Nm), which
is indicative of mild wear, not of severe wear.
Consequently, the five cemented carbides all have
good resistance to the dry sliding wear, although this
could certainly be maximized by appropriate composi
tional tailoring, in particular, by adjusting the Fe/Co
ratio to 1 (WC-(4 wt.%Co+4 wt.%Fe+2 wt.%Ni).
The differences between the SWRs, and therefore
between the wear resistances, of these five cemented
carbides observed in Figure 4 correlate well with the
severity of the wear damage observed by SEM. By way
of example, Figure 6 shows SEM micrographs of the
worn surfaces at the end of the 20 N tribological tests,
and Table 3 lists the elemental chemical composition
determined by EDS at selected locations (marked by
numbers). It is evident in these SEM images that there
is formation of tribolayers (darker areas), which accord
ing to the EDS analyses contain W, metals (Co, Fe, and
Ni as applicable), Al, and abundant O. The presence of
W and Al in the tribolayers indicates that they contain
WC and Al2O3, this last logically as a result of the wear
and subsequent matter transfer from the Al2O3 coun
ter-ball. However, it stands out that the O content is
too high, far above that predicted for Al2O3, thus indi
cating that there are other oxides which had to have
been formed by the in-situ oxidation of both the WC
and the metals, and their possible reaction, during the
tribological tests. Another interesting feature of the
tribolayers is that they are, to a greater or lesser extent,
cracked. Also, in general, the tribolayers have relatively
smooth surfaces and are well adhered to the parent
cemented carbide. However, there are some zones
within the tribolayers where the wear debris is still
visible, is only partially crushed, and seems loosely
adhered. Importantly, the extent of worn surface cov
ered by tribolayer depends on the Fe/Co ratio. Thus,
the coverage is only partial for the cemented carbides
sintered without Fe (WC-(8 wt.%Co+2 wt.%Ni); Figure 6
(a)) as well as with Fe/Co ratios of 1/3 (WC-(6 wt.%Co
+2 wt.%Fe+2 wt.%Ni); Figure 6(b)) and 1 (WC-(4 wt.%
Co+4 wt.%Fe+2 wt.%Ni); Figure 6(c)), very extensive for
the cemented carbide sintered with an Fe/Co ratio of 3
(WC-(2 wt.%Co+6 wt.%Fe+2 wt.%Ni); Figure 6(d)), and
almost total for the cemented carbide sintered without
Co (WC-(8 wt.%Fe+2 wt.%Ni); Figure 6(e)). The surface
of the cemented carbide not covered by tribolayer
(lighter areas) seems quite smooth and well polished,
although some superficial grooves are still observable.
This last is especially noticeable for the cemented car
bide with Fe/Co ratio of 1 (WC-(4 wt.%Co+4 wt.%Fe
+2 wt.%Ni; Figure 6(c)), thus indicating that this
cemented carbide is still in an earlier stage of wear.
The presence of Al in the worn surfaces can also be
used as another comparative indicator of the wear
resistance. Certainly, the greater the Al content in the
worn surface, the greater the wear resistance of
the corresponding cemented carbide because it wore
the Al2O3 counter-ball more. According to the EDS
analysis results in Table 3, the worn surface of the
cemented carbide with Fe/Co ratio of 1 (WC-(4 wt.%
Co+4 wt.%Fe+2 wt.%Ni)) is the one with the highest
content of Al2O3 debris, thus indicating that this
cemented carbide has greater wear resistance than
the rest. This observation is line with the rest of the
tribological results (i.e., lower SWRs, and lower severity
of the wear damage).
Both the values of the SWRs and the wear damage
observed in the worn surfaces thus indicate that the
five cemented carbides wore by abrasion, which first
is caused by the asperities of the counter-ball (i.e.,
two-body wear) and then the combined action of the
counter-ball and the dislodged material trapped
under the contact (i.e., three-body wear). In addition,
wear occurred by both plastic deformation and frac
ture. In particular, initially, the two-body wear
abraded the surface of the cemented carbides,
Figure 5. Dependence on the binder composition of both the
specific wear rates at 20 N load and the (a) hardness or (b)
porosity for the five WC-10 wt.%(Co+Fe+Ni) cemented car
bides pressureless sintered with different Fe/Co ratios.
JOURNAL OF ASIAN CERAMIC SOCIETIES 5
7. causing the formation of grooves in the contact zone
by plastic deformation and eventually leading to the
extrusion and pull-out of metal binder. The accumu
lated plastic deformation and the microstructural
defects ultimately resulted in pull-out of the WC
grains as well, which essentially dictated the onset
of the three-body wear. The wear debris from both
the cemented carbide and the counter-ball trapped
under the contact then abraded more markedly the
surface of the cemented carbides, causing much
greater microstructural damage. Logically, the longer
the sliding time, the greater the accumulated wear
damage. In addition, this wear debris under the con
tact was repeatedly fractured and fragmented, and
was re-embedded into the wear surface thus resulting
in the formation of partially cracked tribolayers.
Evidently, the extent of worn surface covered by tri
bolayer increased with the progressive removal of
material and the attendant wear-debris accumulation.
In addition, the heat generated by friction caused the
partial oxidation of the tribolayers. With this scenario,
wear correlates well with hardness because it essen
tially reflects the residual porosity of the cemented
carbides. Clearly, the porosity provided critical defects
in the microstructure from which fracture could initi
ate more easily, resulting in more in-depth material
removal in the form of WC grain pull-out, and this,
together with the Al2O3 particles, forms the hard wear
debris causing the third-body abrasion. While the
residual porosity is the major factor ultimately
responsible for the wear resistance, there are other
minor factors also affecting it. Thus, for example, the
Figure 6. SEM micrographs of the worn surface at the conclusion of the tribological tests at 20 N load for the five WC-10 wt.%(Co
+Fe+Ni) cemented carbides pressureless sintered with different Fe/Co ratios: (a) Fe = 0, (b) Fe/Co = 1/3, (c) Fe/Co = 1, (d) Fe/
Co = 3, and (e) Co = 0. The crosses indicate the locations where EDS analyses were performed, the results of which are presented in
Table 3.
Table 3. Elemental chemical composition (wt.%) determined by EDS at the locations within the worn surfaces of the five WC-10 wt.
%(Co+Fe+Ni) cemented carbides with different Fe/Co ratios indicated in Figure 6.
Element
Without Fe Fe/Co = 1/3 Fe/Co = 1 Fe/Co = 3 Without Co
Point(1) Point(2) Point(1) Point(2) Point(1) Point(2) Point(1) Point(2) Point(1) Point(2)
W 47.11 64.80 35.11 84.55 18.71 81.88 3.22 97.11 54.00 89.77
Fe − − 1.85 7.17 3.79 4.77 42.31 1.00 4.47 4.23
Co 5.26 4.62 15.08 3.18 12.59 5.02 1.22 0.57 − −
Ni 2.04 1.53 4.46 3.39 8.43 3.04 0.21 1.00 0.98 1.58
Al 15.69 1.66 14.53 1.71 16.25 2.23 15.15 0.32 9.21 0.44
O 39.90 27.39 28.97 − 40.23 3.07 37.89 − 31.33 3.98
6 F. DJEMATENE ET AL.
8. contiguity of the WC grains gradually increased with
increasing Fe/Co ratio (see Table 2), making pull-out
of the WC grains increasingly more difficult. Also, as
seen in Figure 2, the cemented carbides sintered with
Fe/Co ratios of 1 (WC-(4 wt.%Co+4 wt.%Fe+2 wt.%Ni))
and 3 (WC-(2 wt.%Co+6 wt.%Fe+2 wt.%Ni)) as well as
without Co (WC-(8 wt.%Fe+2 wt.%Ni)) contain hard
M6C phase, whose formation then reduced the
amount of metal binder thus on the one hand
increasing the resistance to plastic deformation, but
on the other, because of its hardness, increased the
severity of the three-body abrasion once pulled-out.
Finally, the cemented carbides sintered with an Fe/Co
ratio of 3 (WC-(2 wt.%Co+6 wt.%Fe+2 wt.%Ni)) and
without Co (WC-(8 wt.%Fe+2 wt.%Ni)) could also have
weakened interfaces due to the poorer wettability of
WC in Fe, which may have contributed to its greater
wear. Lastly, it is worth mentioning that the greater
SWRs with increasing applied load are due to the
greater pressure contact acting during the two- and
three-body wear processes, and thus the greater
severity of the abrasions.
4. Conclusions
Five WC-10 wt.%(Co+Fe+Ni) cemented carbides with
micrometer-grained microstructures were fabricated
by pressureless sintering at 1400°C using a fixed con
centration of Ni (2 wt.%) but different Fe/Co ratios. The
resulting cemented carbides were characterized micro
structurally, and their dry sliding wear performances
compared critically at various loads. Based on the
results and analyses, the following conclusions can be
drawn:
1.The Fe/Co ratio affected the microstructure of
these cemented carbides slightly, with the contiguity
of the WC grains continuously increasing as the Fe/Co
increased. Also, although all the cemented carbides are
almost fully dense, both the absolute density and the
degree of densification first increased and then
decreased with increasing Fe/Co ratio, with the max
ima occurring for Fe/Co = 1.
2.As a result of their residual porosity, these WC-
10 wt.%(Co+Fe+Ni) cemented carbides were first
increasingly harder as the Fe/Co ratio increased up to
1, and then increasingly softer with further increase of
the Fe/Co ratio.
3.The wear performance of these WC-10 wt.%(Co
+Fe+Ni) cemented carbides correlated inversely with
the porosity, and thus directly with the hardness.
Hence, the densest and hardest of these cemented
carbides (that fabricated using an Fe/Co ratio of 1)
had the lowest coefficients of friction and specific
wear rates, and underwent the least microstructural
damage. There were, however, other minor factors
also affecting the wear resistance.
4.Dry sliding wear occurs by abrasion induced both
by plastic deformation and especially by fracture. In all
cases, there is formation of tribolayers and mass trans
fer from the counter-ball, but the extent of these phe
nomena depend on the binder composition.
5.It is feasible to optimize the wear resistance of the
WC-(Co+Ni+Fe) cemented carbides for tribological
applications by a judicious choice of their binder
composition.
Acknowledgments
The authors thank the Algerian company Ceramique
Boumerdes and the Scientific Research Project Unit of the
Kocaeli University (Turkey) for the support provided during
this work. Fares Djematene thanks Prof. Kamal Taibi for fruit
ful assistance and guidance. Angel L. Ortiz gratefully
acknowledges support from the Junta de Extremadura
(GR18149).
Disclosure statement
No potential conflict of interest was reported by the authors.
References
[1] Chang S-H, Chen S-L. Characterization and properties
of sintered WC–Co and WC–Ni–Fe hard metal alloys. J
Alloys Compd. 2014;585:407–413.
[2] Fang ZZ, Koopman MC, Wang H. Cemented tungsten
carbide hardmetal–an introduction. In: Sarin VK, edi
tor. Comprehensive hard materials. Oxford (UK):
Elsevier; 2014. p. 123–137.
[3] Bounhoure V, Lay S, Charlot F, et al. Effect of C content
on the microstructure evolution during early solid
state sintering of WC–Co alloys. Int J Refract Metals
Hard Mater. 2014;44:27–34.
[4] Fernandes C, Senos A. Cemented carbide phase dia
grams: a review. Int J Refract Metals Hard Mater.
2011;29(4):405–418.
[5] Ren X, Miao H, Peng Z. A review of cemented carbides
for rock drilling: an old but still tough challenge in
geo-engineering. Int J Refract Met Hard Mater.
2013;39:61–77.
[6] Chen J, Liu W, Deng X, et al. Tool life and wear
mechanism of WC–5TiC–0.5VC–8Co cemented car
bides inserts when machining HT250 gray cast iron.
Ceram Int. 2016;42(8):10037–10044.
[7] Ortner HM, Ettmayer P, Kolaska H. The history of the
technological progress of hardmetals. Int J Refract Met
Hard Mater. 2014;44:148–159.
[8] Yih SWH, Wang CT. Tungsten: sources, metallurgy,
properties, and applications. New York (NY): Plenum
Press; 1979.
[9] Lee G-H, Kang S. Sintering of nano-sized WC–Co pow
ders produced by a gas reduction–carburization pro
cess. J Alloys Compds. 2006;419(1–2):281–289.
[10] Shon I-J, Kim B-R, Doh J-M, et al. Properties and rapid
consolidation of ultra-hard tungsten carbide. J Alloys
Compds. 2010;489(1):L4–L8.
[11] Chang S-H, Chang M-H, Huang K-T. Study on the sin
tered characteristics and properties of nanostructured
JOURNAL OF ASIAN CERAMIC SOCIETIES 7
9. WC–15 wt%(Fe–Ni–Co) and WC–15 wt%Co hard metal
alloys. J Alloys Compds. 2015;649:89–95.
[12] Toller L, Liu C, Holmström E, et al. Investigation of
cemented carbides with alternative binders after CVD
coating. Int J Refract Met Hard Mater. 2017;62
(PartB):225–229.
[13] Polini R, Delogu M, Marcheselli G. Adherent diamond
coatings on cemented tungsten carbide substrates
with new Fe/Ni/Co binder phase. Thin Solid Films.
2006;494(1–2):133–140.
[14] Gao Y, Luo B-H, He K-J, et al. Effect of Fe/Ni ratio on the
microstructure and properties of WC-Fe-Ni-Co cemen
ted carbides. Ceram Int. 2018;44(2):2030–2041.
[15] Boukantar A-R, Djerdjare B, Guiberteau F, et al. Spark
plasma sinterability and dry sliding-wear resistance of
WC densified with Co, Co+Ni, and Co+Ni+Cr.
Int J Refract Met Hard Mater. 2020;92:105280.
[16] Chang S-H, Chang P-Y. Investigation into the sintered
behavior and properties of nanostructured WC–Co–Ni–
Fe hard metal alloys. Mater Sci Eng A. 2014;606:150–156.
[17] Schubert WD, Fugger M, Wittmann B, et al. Aspects of
sintering of cemented carbides with Fe-based binders.
Int J Refract Met Hard Mater. 2015;49:110–123.
[18] Guilemany JM, Sanchiz I, Mellor BG, et al. Mechanical-
property relationships of Co/WC and CoNiFe/WC hard
metal alloys. Int J Refract Metals Hard Mater.
1993–1994;12(4):199–206.
[19] Zhao Z, Liu J, Tang H, et al. Investigation on the
mechanical properties of WC–Fe–Cu hard alloys.
J Alloys Compds. 2015;632:729–734.
[20] Gao Y, Luo B-H, He K-J, et al. Mechanical properties and
microstructure of WC-Fe-Ni-Co cemented carbides pre
pared by vacuum sintering. Vacuum. 2017;143:271–282.
[21] American Society for Testing and Materials
International (ASTM International). Standard test
method for wear testing with a pin-on-disk apparatus.
West Conshohocken, PA (US): Standard No. ASTM G99-
17; 2017.
[22] Guo Z, Xiong J, Yang M, et al. WC–TiC–Ni cemented
carbide with enhanced properties. J Alloys Compds.
2008;465(1–2):157–162.
[23] Pirso J, Letunovitš S, Viljus M. Friction and wear beha
viour of cemented carbides. Wear. 2004;257
(3–4):257–265.
[24] Sun J, Zhao J, Gong F, et al. Development and applica
tion of WC-based alloys bonded with alternative bin
der phase. Crit Rev Solid State. 2019;44(3):211–238.
[25] Upadhyaya GS, Bhaumik SK. Sintering of submi
cron WC-10wt.% Co hard metals containing nickel
and iron. Mater Sci Eng A. 1988;105–106
(Part1):249–256.
[26] Ojo-Kupoluyi O, Tahir S, Baharudin B, et al. Mechanical
properties of WC-based hardmetals bonded with iron
alloys–a review. Mater Sci Tech. 2017;33(5):507–517.
8 F. DJEMATENE ET AL.
![FULL LENGTH ARTICLE
A comparative study of the dry sliding wear of WC-10wt.%(Co+Fe+Ni)
cemented carbides pressureless sintered with different Fe/Co ratios
Fares Djematenea
, Boubekeur Djerdjarea
, Aniss-Rabah Boukantara
, Amine Rezzouga,b
, Said Abdia
,
Ismail Daouda
and Angel L. Ortizc
a
Laboratory of Science and Materials Engineering (LSGM), University of Sciences and Technology Houari Boumediene, Algiers, Algeria;
b
Research Centre in Industrial Technologies (CRTI), Algiers, Algeria; c
Departamento de Ingeniería Mecánica, Energética y de los Materiales,
Universidad de Extremadura, Badajoz, Spain
ABSTRACT
Compositional effects on the dry sliding wear resistance of micrometer-grained WC-10 wt.%(Co
+Fe+Ni) cemented carbides pressureless sintered with 2 wt.% Ni but different Fe/Co ratios were
investigated. Their microstructures are very similar except for the contiguity of the WC grains,
which increased with increasing Fe/Co ratio. Also, these cemented carbides are all almost fully
dense, but with the degree of residual porosity exhibiting a complex trend with increasing Fe/Co
ratio (first decreasing and then increasing). The greatest densification was reached for an Fe/Co
ratio of 1. The reverse trend was observed for the hardness, which reached HV10=1090 kg/mm2
for Fe/Co = 1, indicative that it is dictated essentially by the porosity. The wear resistance
correlated inversely with the porosity (and thus directly with the hardness), so that the densest
(and thus the hardest) of these cemented carbides (the one sintered with a Fe/Co ratio of 1) also
exhibited the lowest coefficients of friction, the lowest specific wear rates, and the lowest
microstructural damage. The wear mode was abrasion, with the wear mechanism being plastic
deformation and especially fracture. Thus, optimization of the wear resistance of WC-(Co+Fe+Ni)
cemented carbides for tribological applications is feasible by a judicious design of their binder
composition.
ARTICLE HISTORY
Received 16 March 2020
Accepted 2 August 2020
KEYWORDS
Cemented carbides; sliding
wear resistance; WC; metal
binder; pressureless sintering
1. Introduction
Cemented carbides, also known as hardmetals, are an
outstanding subfamily of cermets whose microstruc
ture is specifically constituted by grains of a hard
refractory carbide embedded in a metal binder [1–4].
They possess a remarkable combination of mechanical
properties because the carbide grains offer high hard
ness and stiffness, whereas the metal binder offers
high ductility and toughness, and are therefore in
high demand for a great multitude of engineering
applications and especially for those requiring high
wear resistance. Representative examples are in the
fields of drilling, machining, turning, milling, and cut
ting tools [5–10], to name but a few.
WC with Co binder is doubtless the best exponent
of the cemented carbides, despite it being widely
acknowledged today that using Co as cementing
phase has several disadvantages. These include con
cerns about its high cost, price variability, and environ
mental toxicity [11–14]. There is thus growing interest
in substituting, at least partially, Co with other metal
binders [15], with the combination Fe and Ni being
a promising alternative [16–20]. For example, it has
been demonstrated that WC-(Co+Fe+Ni) cemented
carbides have similar hardness but greater fracture
toughness than their WC-Co counterparts [11].
Interestingly, a recent study on WC-(Co+Fe+Ni) cemen
ted carbide with equal Co content but varied Fe/Ni
ratios demonstrated that their mechanical properties
depend on their exact binder composition, with the
hardness, transverse rupture strength, and wear resis
tance increasing, but the fracture toughness and corro
sion resistance decreasing, as the Fe/Ni ratio
increases [14].
Despite its interest, detailed understanding of other
compositional effects on the wear resistance, the most
demanded property, of the WC-(Co+Fe+Ni) cemented
carbides is lacking. With this in mind, the present study
was undertaken to investigate in detail, using the same
experimental platform, how substituting Co with Fe
under constant Ni concentration affects the wear per
formance of WC-(Co+Fe+Ni) cemented carbides fabri
cated by conventional pressureless sintering. To this
end, five of these WC-(Co+Fe+Ni) cemented carbides
were fabricated under identical conditions, containing
2 wt.% Ni but different Fe/Co ratios up to a total of
10 wt.% metal binder, and their dry sliding wear resis
tance compared critically at three different loads. The
2 wt.% Ni proportion is adequate for this type of
cemented carbide and was fixed at that value so that
the only processing variable was then the gradual
CONTACT Angel L. Ortiz alortiz@unex.es Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura,
Badajoz 06006, Spain
JOURNAL OF ASIAN CERAMIC SOCIETIES
https://doi.org/10.1080/21870764.2020.1806193
© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of The Korean Ceramic Society and The Ceramic Society of Japan.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)