Fatigue-Resistant Heterogeneous Gradient Nanocrystalline NiTi Shape Memory Alloy Fabricated by Pre-Strain Laser Shock Peening

NiTi shape memory alloy (SMA) has been widely used in many fields for its superelastic and behaviors. The compressive fatigue life of is very high, but the tensile bending relatively low. In this study, pre-strain laser shock peening (LSP) introduced to solve these challenges. Different heterogeneous nanostructured (containing B2, B19′ phases, precipitates including Ni3Ti Ni4Ti3) gradient residual stress layers were created by controlling during LSP treatment. highest under maximum strain 2.4% reached over 34,000 cycles, 33 times that untreated sample. proposed method provides a new avenue fabricate fatigue-resistant SMA.