Designation: Wrought Al AlloysNon-heat-treatable alloys• 1xxx series (Super-purity and commercial-purity aluminium)• 3xxx series (Al-Mn and Al-Mn-Mg alloys)• 5xxx series (Al-Mg alloys)• 8xxx series (Miscellaneous alloys)Heat-treatable alloys• 2xxx series (Al-Cu and Al-Cu-Mg alloys)• 6xxx series (Al-Mg-Si alloys)• 7xxx series (Al-Zn-Mg and Al-Zn-Mg-Cu alloys)
Al-Cu alloys (2xxx series)• Cu (Tm = 1085oC, FCC structure)• Good solubility up to 5.65% at 548oC (eutectic).• Eutectic reaction gives :o α phase (5.65%Cu) – ductile+o θ phase (CuAl2-52.75%Cu) – brittle.• Precipitation hardening – by forming θ phase inα matrix, gives high strength and toughness.
Equilibrium phase diagram Al-Cu• Eutectic phase:consists of alternate lamella structureof α and θ phases,resembling pearlite in carbonsteels, which give high strength butbrittle.• Hypoeutectic:> 5% Cu, cooling is in equilibrium,grain boundaries of α phasesurrounded by (α+θ ) eutectic phase -reduced toughness.< 5% Cu, α phase in some casessurrounded by θ phase.• Hypereutectic• Cu 33%, too brittle due tohigh amount of θ phase.Al-Cu alloys (2xxx series)
Properties & ApplicationsProjetar tabelas para um novo banco de dadosFuel TanksProperties:• High strength (2119: σTS 505 MPa).• Good creep strength at high temp.• High toughness at cryogenic temp.• Good machinability.Welding wire
• Equilibrium cooling gives α + θ (CuAl2) - non-coherent precipitates with the matrix(starting at A). But Quenching give supersaturated solid solution (α’ phase) - higheramount of Cu can be dissolved in the matrix.•Coherent θ ’ changes to non-coherent precipitates θ with increasing ageing time (tryto get back to equilibrium) less strength due to no distortion within the lattice. (Overaging)Age- Hardening Mechanism in Al - Cu
Al-Cu-Mg alloys (2xxx series)Applications:• pistons, rivets for aircraftconstructions• Miner amount of Mg (0.2%) modifies the precipitationprocess, resulting in greater age-hardening.Properties:• High strength (2024: σTS 520 MPa).• high toughness.2024-T4 (solutionheat treated) plateshowingredistribution ofconstituents2024 heatedingot showingsolubleAl2CuMg.Airplane structureAluminum pistons and devices forthermal shock used in airplanes
Designations of Cast Aluminum Alloys1xx.x series• Second two digits indicatethe minimum percentage ofAl, Ex: 150.x 99.50% Al.• Last digit (after decimalpoint) indicates product forms.1 = casting, 2 = ingot2xx.x to 9xx.x series• Second two digits identifythe different aluminum alloys.• Last digit (after decimalpoint) indicates product forms
Al-Cu alloyProjetar tabelas para um novo banco de dadosAerospacehousing(201.0)• Strength and hardness - at T up to 250oC –a combination of precipitation hardening together with dispersionhardening by intermetallic compounds.• Strength is higher than other cast Al alloys and comparable to wrought Alalloys.Note: Have casting problem with hot-tearingProperties:σy 345-480 MPa and σTS 415- 550MPa due to high response to ageingApplications:Elevated temperature applications.Ex; diesel engine pistonsair-cooled cylinder heads foraircraft.Flywheel housing(295.0)