The effect of age hardening on the microstructure,martensitic transformation behavior,and shape memory properties of the(Ni50Ti30Hf20)95V5 alloy was investigated by scanning electron microscopy,transmission electron microscopy,X-ray diffraction,differential scanning calorimetry,microhardness,and bending tests.The results demonstrate a significant influence of V addition on the microstructure of the alloy.V addition leads to the formation of a(Ni,V)2(Ti,Hf)-type Laves phase,which coexists with B19'martensite at room temperature.Aging at 550 ℃ results in precipitation hardening due to the formation of nano-scale orthorhombic H-phase,with the peak hardness observed after 3 h of aging.The alloy at peak hardness state exhibits higher transformation strain and lower unrecovered strain compared to the solution-treated sample.The aged sample achieves a maximum transformation strain of 1.56％under 500 MPa.
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