Contributions to high temperature strengthening from three types of heat-resistant phases formed during solidification, solution treatment and ageing treatment of Al-Cu-Mn-Ni alloys respectively

摘要

The high temperature strengths of Al-5Cu-lMn-xNi alloys as-cast, in T4 temper and in T6 temper were obtained by tensile test at 300 ℃. Microstructure evolution was examined by optical microscope, SEM-EDS and TEM-EDS/ SAD. The contributions to high temperature strengthening from three types of heat-resistant phases formed during solidification, solution treatment and ageing treatment respectively are discussed in this study and carefully gazed. It is found that the heat-resistant phases formed during solution treatment and during ageing treatment have much greater contribution to high temperature strengthening than that formed during sobdifkation. Not consistent with the traditional realizations, can the 0" phase formed during ageing treatment in Al-Cu-Mn-Ni alloy act as a heat-resistant strengthening phase at high temperature. Thus, a new point of view is strongly confirmed that: strengthening the matrix by small dispersoid particles formed during solution treatment and by fine precipitates formed during ageing treatment should gain much more attention.