This document discusses shape memory alloys (SMAs), specifically focusing on nickel-titanium (Ni-Ti) alloys. It defines SMAs as materials that can return to a predetermined shape after deformation through heating or cooling. SMAs exist in two phases, austenite and martensite, and transition between the phases through temperature changes, allowing the material to change shape. Common applications of Ni-Ti SMAs include uses in biomedical devices, robotics, and sensors due to properties like biocompatibility and high strain recovery. The document compares Ni-Ti SMAs to other materials like copper-based SMAs and stainless steel.

1. By:
Prashant singh
(IMI2011003)

2. • Introduction.
• Shape Memory Alloy.
• Operation principle.
• Types of SMA
• Ni-Ti Alloy.
• Advantages & Disadvantages of Ni-Ti Alloy
• Ni-Ti Vs. Copper based SMA.
• Ni-Ti Vs. stainless steel.
• Applications
• References

3. • Smart materials are designed materials that have one or more
properties that can be significantly changed in a controlled
fashion by external stimuli, such
as stress, temperature, moisture, electric or magnetic fields.
• Types of Smart material:
• Shape memory alloy
• Piezoelectric
• Thermoelectric materials
• Thermochromic
• Photochromic, etc.

4. • SMA are the Materials which have the ability to return to a
predetermined shape when heated or cooled, or below its
transformation temperature.
• When it is heated above its transformation temperature it
undergoes a change in crystal structure which causes it to
return to its original shape.
• The most common shape memory material is an alloy of nickel
and titanium called Nitinol
• This particular alloy has very good electrical and mechanical
properties, long fatigue life, and high corrosion resistance.

5. • SMA has two stable phases
1) Austenite (high temperature phase)
2) Martensite (low temperature phase)
Fig. 1: Different phases of a shape memory alloy

6. (a) (b)
Fig. 2: (a)Temperature-induced phase transformation of a shape memory alloy without
mechanical loading. (b) hysteresis curve

7. • Types of SMA
• One way SMA
• Cu-Al-Ni Alloy, Ti51Ni49
• Two way SMA
• Types of Alloys
• Ni-Ti
• Copper

8. • The term nitinol is derived from its composition and its
place of discovery: (Nickel Titanium-
Naval Ordnance Laboratory).
• Nitinol is actuator, sensor and heater all in one material
• Nitinol thin film actuators have attracted significant
development efforts in the recent past years.
• Nitinol films normally less than 10m in thickness were
deposited on silicon, glass or polymeric substrates by
sputter deposition.

9. Advantages
• Simple training mechanism
• High power/weight ratio
• Noiseless and silent training
• High corrosion resistance
• Can be controlled with electrical current
Disadvantages
• Highly controlled fabrication process required (1% change in
composition results in 20°C temperature variation)
• Low energy conversion efficiency (5%)

10. • .
Ni-Ti based SMA
• Recoverable strain(8%)
• Shape change temperature
range (-200 to +200 C)
• High resistance to corrosion
• Consist of 50% Ni and 50%
Ti
• Expensive material and
highly controlled Fabrication
process.
Copper based SMA
• Recoverable strain(4-5%)
• Shape change temperature
range (-200 to +150 C)
• Low resistance to
corrosion.
• Consist of 80% Cu and
20% Zn+Al.
• Less expensive material
and Metallurgical process.

11. Nitinol vs Stainless Steel
Property Nitinol Stainless Steel
Recovered Elongation 8% 0.8%
Biocompatibility Excellent Fair
Effective Modulus** approx. 48 GPa 193 GPa
Torqueability Excellent Poor
Density 6.45 g/cm3 8.03 g/cm3
Magnetic No Yes
Resistivity
80 to 100 micro-
ohm*cm
72 micro-ohm*cm

12. • MEMS electrical & thermal Actuator
• Micro-grippers
• Aerospace and Naval Applications
• Medical
• Dentistry
• Repair broken bones
• Replace damage discs
• Cellular phones
• Robotics arm
• Fire alarm sensor
• Arts

13. • Ackland G. J., “Atomistic modelling of the shape memory effect”, eprint
arxiv:condmat/0509456, september 2005
• Ming H. Wu and L. Mcd. Schetky,” INDUSTRIAL APPLICATIONS FOR SHAPE MEMORY
ALLOYS”, proceedings of the international conference on shape memory and superelastic
technolgies, pacific grove, california, P.171-182 (2000).
• Milenko braunovic, senior member, ieee, and c. Labrecque,” shape-memory alloy mechanical
contact devices”, IEEE TRANSACTIONS ON COMPONENTS, PACKAGING, AND
MANUFACTURING TECHNOLOGY-PART A, VOL. 19, no. 3, september 1996
• “Shape-memory alloys – metallurgical solution looking for a problem”, metallurgia, vol.
51,no. 1, january 1984, pp. 26–29
• Wu shanqiang, huang peipei,” A micro wall-climbing robot using shape memory alloy”, 2011
second international conference on digital manufacturing & automation.
• Chen-luen shih, bo-kuai lai, harold kahn, stephen m. Phillips, senior member, IEEE, and arthur
H. Heuer,” A robust co-sputtering fabrication procedure forTini shape memory alloys for
MEMS”, IEEE JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 10, no.
1, march 2001