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The deformation behavior of Ti-50.9at%Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858Mini Bionix test machine. The alloy were aged at 500℃ for an hour before being machined into specimens. The compression experiments were conducted at 20℃ and the variety of dynamic loads were controlled by the strain rate, which was 3mm/min, 15mm/min, 30mm/min and 50mm/min, respectively. The experimental results indicate that in the case of 3mm/min, stress-induced martensitic transformation occurs at about 350MPa when loading and reverse transformation at about 200MPa when unloading, during which the aged Ti-50.9at%Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3% with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i.e stress (strain) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5%.
The deformation behavior of Ti-50 .9% Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858 Mini Bionix test machine. The compression were conducted at 500 ° C for an hour before being machined into specimens. The compression experiments were conducted at 20 ° C and the variety of dynamic loads were controlled by the strain rate, which was 3mm / min, 15mm / min, 30mm / min and 50mm / min, respectively. The experimental results indicate that in the case of 3mm / min, stress- induced martensitic transformation occurs at about 350 MPa when loading and reverse transformation at about 200 MPa when unloading, during which the aged Ti-50.9 at% nickel alloy shows recoverable nonlinear pseudoelastic strain of 4.3% with the residual strain of 1.2% reserved. rate increasing, the area encloses by loading-curve and unloading-curve, ie stress (strain) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5%.