The production of cualco shape memory alloys, and investigation of physical properties

In this study, the effect of Co content on crystal structure, transformation temperature and microstructure of Cu-Al-Co shape memory alloy system were investigated. It was detected that similar to most other copper-based systems, Cu-Al-Co alloy system had also 18R type martensitic structure. The transformation temperatures was found higher than 250 °C for the whole range of compositions of this alloy while a regular increase or decrease in the value with Co content was not observed. This was attributed to variation of Cu and Al contents while the Co content was changed. The microstructural examination of four different Cu-Al-Co alloys indicated the presence of martensite phase together with precipitates. It was realized that the size of precipitates increases with increasing Co content. Additional to that, if the average hardness values obtained from the Vickers micro-hardness tests are compared, it can be stated that the hardness value increases with increasing Co content. All these results point out that increasing Co content increases the strength in Cu-Al-Co shape memory alloy system. Keywords: Shape memory alloy; participate; martensite; Vicker hardness.