Achieving ultralow elastic modulus in TiNi alloy by controlling nanoscale martensite phase

A low elastic modulus is urgently expected for bio-implant to avoid the harmful stress-shielding effect. Here, by using electroplastic rolling deformation, an ultralow elastic modulus of E ∼29 GPa was achieved in a Ti-50.7at%Ni alloy. The low elastic modulus can be attributed to the existence of nanoscale lamellas of low-elastic modulus martensite phase with a high fraction of 16.2% and the sluggish stress-induced martensitic transformation and reorientation of martensite variants.