The Relaxation-type Internal Friction And Its Stability In Ti₅₀Ni₃₀Cu₂₀ Shape Memory Alloys

Attributing to excellent superelasticity and high damping property,Ti-Ni-based shape memory alloys especially Ti-Ni-Cu ternary system has agood application prospect in damping materials. In the present work, theinternal friction (IF) behavior of Ti50Ni30Cu20shape memory alloys afterdifferent heat treatment processings was investigated. The process underwhich a relaxation-type IF peak occurred was thus obtained and itsstability condition was also achieved. The results show that, the process ofsealing-solution treatment, is favorable for producing remarkablerelaxation phenomenon, by which the damping capacity of the alloys canreach a high IF value of about0.1within the temperature range of220~260K. Further, the relaxation phenomenon can be retained upon annealingin the air below973K; while upon annealing above973K, the relaxationphenomenon disappears. In addition, the tensile and compressed tests onthe specimen after sealing-solution process indicate that, both the flowstress and elasticity modulus decrease while the hardness increases.