The influence of thermo-mechanical treatment on phase transformation and shape memory effect of CuAl9Fe4Ni2 alloy

Shape memory alloys can return to their original shape by reversible martensitic transformation. The shape memory effect of these alloys has been considered to relate to phase transformation, especially martensite transformation. In the copper-aluminum alloys containing Fe and Ni additives, the relationship between the martensitic transformation and shape memory effect occurs by applying a thermo-mechanical deformation and heat treatment process. This paper presents the phase transformation of the CuAl9Fe4Ni2 alloy that suffered from the deformation and heat treatment process. The samples were heated above 1173 degrees K for homogenization. Then, they were rolled with an appropriate degree of strain to prepare the good conditions for the next steps. They were heated again to 1173 degrees K, then quenched in water to 373 degrees K, and then cooling down in cold water to form martensites with fine grain sizes. Next, the samples underwent cold deformation to create a fine grain in the structure and a favorable distribution for the shape memory process. Finally, the samples were shaped and heated at 843 degrees K to decompose the martensite phase and return to their original shape. The phase transformation and the structure of martensite were determined by modern analytical techniques. The results show that the shape memory level was up to 80%.

Automated summary

In this study, the phase transformation and structure of martensite in CuAl9Fe4Ni2 alloy were analyzed through a thermo-mechanical deformation and heat treatment process. The results show that after undergoing various steps including heat treatment, cold deformation, and shaping, the shape memory level of the samples reached up to 80%.