Investigation On Fabrication And Properties Of Cu-Zn-Al Shape Memory Alloy Microwires

In this paper, The high vacuum arc melting was used to prepare the ingot ofCu69.12Zn27.13Al3.75, continuous Cu-Zn-Al shape-memory microwires of differentdiameters are fabricated by Taylor-wire drawing and cold drawing technique. Themorphology and microstructure of the wires were observed by SEM?OM and thecomposition, phase, transformation temperature are analysed by differential DSCXRD and EDS. Different quenching temperatures have different effects onmicrostructure and mechanical properties.When the temperature is below820?,the wires are biphase, when the temperature is higher than820?, microstructure ismartensite. Although the same temperature is used, due to the higher cooling speed,the smaller diameter wires can not become single-phase after quenching. Whentemperature is raised?quenching microstructure can be converted into martensite.Strength increases and plasticity decreases with decreasing wire diameter.Annealing can significantly improve plasticity, quenching temperature have greatinfluence on the strength and elongation. Strength increases with increasingtemperature at first and then decreases. Elongation increases with decreasingtemperature.Damping properties, superelasticity and shape memory properties of the wireswere characterized in tension using a dynamic mechanical analyzer (DMA Q800).Studies show that Cu-Zn-Al wires in martensite state have high damping properties,tan mutates during phase changing. Compared with the parent phase, damping ofmartensite phase and in phase transformation process are affected by the strainamplitude and vibration frequency greatly, the interface movement produced energyloss, and the number of moving interface, mobility and mobile distance will beaffected by temperature, frequency, strain. So damping properties will be influenced.The results show that there were size effects in both the transformation stressesand energy dissipation.The stress hysteresis in a mechanical cycle increase withdecreasing wire diameter,varies with diameter following ???D-0.68. The resean isthat when the diameter is smaller, the interface friction is bigger, so stress hysteresisand energy dissipation increase.