Success Stories

STCU Project #3520 (financed by the U.S. for US$ 263,000) is devoted to nanostructured shape memory intermetallic compounds with enhanced transformation temperatures. The (TiZrHf)(NiCuMe) melt-spun ribbons and twin-roll strips with controlled grain size and small size dispersion have been obtained from initially amorphous state by appropriate heat treatments. Pre-alloyed TiNi-base powders have been obtained by the electric-spark erosion technique providing solidification rates of 106–109K/s from liquid and vapor states. Ni-Mn-Ga-X alloy powders by electric spark erosion and ultrasonic assisted severe plastic deformation by ball milling are also envisaged. Details of the processes used and enhancement of shape memory properties due to the nanoscale crystals formed from supercooled metallic liquid or broking microstructure dawn into nanostructured are being studied.
Grain size controlled shape memory alloys with high transformation temperature have high potential for use in automotive and air-space industries. Natural refinement of the parent phase microstructure helps to improve the mechanical properties (to increase strength) and thus fulfill the requirement of thermoelastic phase equilibrium, superelasticity and shape memory accompanying martensitic transformations at increased temperatures.