Study On Thermal Deformation Of Cu-Al-Be Alloys

Superelastic Cu-Al-Be SMA Wires with excellent properities of superelastic is very useful in the application of commerce.In this paper,the properties of a columnar crystal Cu-Al-Be shape memory alloy wire with thermal deformation have been studied to establiash the possibility of practical application in the industrialized production. However,in practical application,Cu-Al-Be shape memory alloy is difficult to ensure that,as long as the emergence of some small deformation,it will be disappear with super-elastic properties.Now the Cu-Al-Be shape memory alloys in the country is still in the laboratory research stage,its heat distortion of the domestic research has yet to see.The subject of a new Cu-Al-Be alloy thermal deformation capacity is studied and obtained a longitudinal columnar structure by heated mold continuous casting process,improving mechanical properties and super elasticity of this two alloy by strengthening texture.At the same time,the properities of alloy wires deformed by using methods such as temperature was comparables with organizations cast.The Cu-Al-Be in the thermal deformation state organizations and the changes in temperature changes the relationship between structure changes of Cu-Al-Be alloy wires in thermal deformation state was studied.Summing up by divided into small and large deformation.At last,the most reasonable thermal deformation process was found to different requirements.Cu-Al-Be SE alloy wires are cast by heated mold continuous casting process at 350mm/min casting speeds.The tensile strength and elongation rate of Cu-Al-Be alloy wire be measured by hest deformation at 400℃,450℃,500℃,550℃,600℃;The repeat bending fatigue life of Cu-Al-Be alloy wires is determined by a self-designed equipment;The phase changes of Cu-Al-Be alloy wires deformed were analyzed with X-ray Diffraction(XRD);Finally,the fatigue fracture of deformed alloy wire be observed at different temperatures by scanning electron microscopy.The result shows that:the Cu-Al-Be alloy wires cast by heated mold continuous casting process can get columnar grain structure.The cylindrical grain structure and mother phase be maintained in deforming at 400℃and 450℃,better mechanical properties.However,not only deformation be more difficult,but also the crack will be appear in the specimen after the deformation at this temperature,the properties of deformed alloy wire be affected greatly.The cracks have been generated from within the cracks and then until the beginning of growth Fault when be drawing and bending. In 500℃,The mother phase and columnar crystal structure of the specimen defomed can be maintained,and with the increase of deformation temperature,cracks have been rare,and more easily deformed.In 500℃,the sample deformed has excellent mechanical properties,the elongation rate up to 40%,bending fatigue life longer, whether it is a large deformation or small deformation can reach more than 80,000 times,with comprarable with casting alloy wire.The deformation at 550℃and 600℃be more easy at 500℃,forging needs one times.However,the sample organization has changed,generating a new phase,cylindrical grain organizations were also damaged at this temperature,so at this temperature,the mechanical properties of the sample deformed be worst,the elongation rate not up to 20 percent,Bending greatly reduce fatigue life of 30,000 times.