Of Melt Superheating Treatment On Microstructures And High Temperature Nical Properties Of Al-Cu Alloy

The melt structure of alloy play an important part in its solidification process, solidification microstructure and function.In recent year,the superheating treatment of alloy melt is a way of inducing alloy melt structure transform by changing melt thermal history. Thus affecting the solidification process, the solidification structure and performance.At present,The research on the behavior of the alloy melt structure transition is still limited to a few alloy system, from the perspective of controlling structure to improve the melt solidification microstructure and properties is still empirical. The article talk about the influence of superheating treatment on solidification microstructures and high temperature mechanical properties by melt superheating treatment on casting Al-Cu alloy.We in order to enrich the solidification theory,and to play a guiding role on finding new technology research and improving high temperature mechanical properties.The results show as follow:Firstly,Temperature and time dependence of electrical resistivities of liquid base of Al-Cu alloys with different components was surveyed by the resistivity experiments. On the p-T curves,we found different characteristics and patterns of abnormal changes along with various alloys.Secondly, Through the department of Al-Cu alloy solidification microstructure observation and XRD tests we found, by superheating treatment the size of the grain significantly refined, the grain morphology is more structured, distributed between phase and phase alloy is more uniform.We think,it mihgt be due to the clusters structure becomes finer and disorderlyin the melt,resulting in lower supercooling degree and higher nucleation rate.Thirdly,by superplastic tensile test for Al-Cu alloys, under the same conditions of temperature and stretching rate,the superplasticity of Al-Cu alloys are significantly improved, elongation are further improved superheating treatment.It might due to the size of the grain become more uniform by superheating treatment thus making the stress concentration region being reduced, the grow rate of connecting holes is reduced. It is result in increasing the elongation.Fourth, By high temperature creep test of Al-Cu alloys, At the same temperature and tensile load, by superheating treatment, the creep rupture strength of Al-Cu alloys are improed.It might because that, by superheating treatment the size of the grain significantly refined, grain morphology is more structured, distributed between phase and phase alloy is more uniform. Therefore, the stress concentration is relative to reduce, thereby resulting in improved the creep rupture strength.