Effects of Co and Al addition on martensitic transformation and microstructure in ZrCu-based shape memory alloys
(School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The effect of ternary alloying element Al and quaternary alloying element Co on the martensitic transformation of ZrCu-based shape memory alloy was investigated. The results show that the addition of Al and Co in ZrCu alloy decreases both the martensitic transformation temperature and the martensitic transformation temperature hysteresis. Transmission electron microscope (TEM) observations reveal that the Cm martensite structure is the preferential formation phase. The intervariant structures in ZrCuAlCo alloy are (021) type I twins, while the dominant substructures inside the martensite variant are the (001) compound twins. With the increase of Co content, tensile fracture strength and strain are improved obviously.
Key words: ZrCu-based alloy; shape memory alloy; martensitic transformation; microstructure