Temperature-dependent cyclic response and microstructure of AlSi10Mg(Cu) alloy

In the present work, the cyclic stress response and microstructure evolution of AlSi10Mg(Cu) alloy at high temperature were investigated. Samples were tested at high temperature, under total strain control and tensile-compression loading (R = −1) until failure. The cyclic stress response was analyzed, as well as the microstructures were examined by TEM. The results demonstrated that the cycle stress response of the studied alloy is experimental temperature dependence. Microstructure analysis indicated the precipitated phase was disruptive changed by high temperature compared to the as-received alloy. A lot of coherent β″-Mg₂Si precipitates and GP zones were observed in the as-received alloy, resulting in sustaining cyclic hardening by pinning effect. At high temperature, the vast majority of the tiny coherency precipitates and clusters transformed to the large semi-coherency Q′ and β′-Mg₂Si precipitates, leading to the sharp decrease of pinning number and the change of dislocation interaction mechanism, which is believed to be one of the reasons for softening. Another reason is that high temperatures can promote dislocations movement.