Research On The Phase-change Nature Of CuZnAl Shape Memory Alloys In Thermal Cycling

Baced on the engeneering application of CuZnAl shape memory alloys,this paper analyzes the variation law of SME and restoring force of the alloys, from the points of the thermomechanical training propertys and the phace change properties of the alloys. Bend method was applied to measure the SME of these alloys. Microstructure was studied by virtue of optical microscope, SEM, XRD and transmission electron microscope.Experiment result indicates that:(1)Wen the pre-deformation is greater than 2.6%(the maximal reversionable pre-deformation of the alloys),the SME will keep a montonic decreasing with the increasing of the pre-deforminng amount, but the decreasing tendency is slowing up;In two-grade ageing heat-treatment technology, parent phace-change is basically comprecated within 15minites,30minites liter,The SME reaches its peak-point.and with the aging time going on,the SME of the alloys will decrease because of the bainite transformation of it.lhour later, the SME decreases severely.(2)When the pre-deforming is not too big(under 5.725%),the restoring stress will increase linearly with the increasing of temperature,and the "temperature-restoring stress" pattern, deduced from Clausius Clapeyron equation, can works well to predict the test temple. When applying the self-made "temperature-restoring stress admeasuring apparaters" to measure restoring stress, limited by the poor stressing duration stiffness of the test sample,its restoring force can't be fully developed in the apparatus, after some appropriate mechanical treatment(reinforcing rib),the experimental findings can mach the data from pattern well,which conforms the feasibility of the temperature-restoring stress pattern.