Effect of adding Si on shape memory effect in Co–Ni alloy system

In this paper, the effect of adding Si to Co–31.5 mass% Ni alloys on fcc–hcp martensitic transformation is investigated. The Co–Ni–Si ternary alloys with different amount of Si from 1 to 5 mass% were prepared. The stacking fault probability of Co–Ni–Si polycrystalline alloys were determined by X-ray diffraction profile analysis and compared with the binary Co–Ni alloy. The results show that the stacking fault probability of the fcc phase of alloys increases with increasing Si content. The effect of Si on phase transformation and shape memory behavior is evaluated. The experimental results show that both the critical strength and the shape memory effect of the ternary alloys will increase by the addition of Si. The improvement mechanism of the shape memory effect by adding Si to binary Co–Ni alloys is discussed.