High-efficiency low driving-force stable bending cooling via fatigue-resistant hierarchical NiTi shape memory alloy

Elastocaloric cooling driven by shape memory alloys (SMAs) is emerging as a promising, environmentally friendly alternative for next-generation refrigeration. However, its widespread application is limited by the high driving forces and low energy efficiency. Here, we introduce an bendinig driven elastocaloric cooling approach that enables significantly reduced driving forces and enhanced energy efficiency. Our approach achieves a high coefficient of performance (COP) of 17.9 and specific cooling power (SCP) of 36140 W/kg at a low specific driving force (SDF) of 11.2 N/mm³. Critically, the specimen demonstrates exceptional durability, sustaining over 5 million cycles under a maximum surface tensile strain of 1.94% through a pre-strained, warm laser shock peening (pw-LSP) treatment. This extraordinary fatigue resistance arises from the formation of a hierarchical microstructure and large compressive residual stress of exceeding 1 GPa. Our findings establish bending-induced elastocaloric cooling as an efficient and durable solution for next-generation sustainable refrigeration.