7D04-T7451铝合金高温性能及组织变化特征

Microstructure characterization and properties of 7D04-T7451 aluminum alloy at high temperatures

通过高温拉伸、SEM、TEM等方法对7D04-T7451铝合金厚板在不同温度下的组织、性能变化及断裂行为进行试验研究。结果表明,随拉伸温度升高,合金的强度降低,伸长率随温度增加而逐渐增加;在较低温度拉伸时,出现了二次析出的现象;当温度超过150℃后,晶内析出相发生了粗化;随温度升高,合金断口逐渐由以位错滑移为主的层片状沿晶断裂转变为以基体/析出相滑脱为主的韧窝断口。

Mechanical properties, microstructure and fracture behaviours of 7D04-T7451 aluminum alloy at different temperatures were studied with high-temperature tensile test, TEM and SEM. The results show that as tensile temperature goes up, the strength of the alloy decreases and the elongation increases. Second precipitation is observed at low temperatures. When tensile temperature exceeds 150°,precipitated phases are coarsened in grains. As tensile temperature goes up, the layer-shaped inter-granular fracture （mainly with dislocation slipping） turns into the dimple fracture （mainly with matrix/precipitated phases slipping）.