预变形对2D12铝合金组织热稳定性和高温力学性能的影响

Effect of pre-deformation on micro-structural thermal-stability and mechanical properties at elevated temperatures of 2D12 alloy

通过拉伸性能测试和透射电镜(TEM)观察等手段,研究预变形对2D12铝合金组织的热稳定性和高温力学性能的影响。结果表明,预拉伸变形能显著增加S相的弥散度,提高合金的时效硬化效应和室温至300℃以内高温下的强度,降低合金断后伸长率。200℃下热暴露500 h后,预变形合金的抗拉强度保留峰值强度的84.76%,伸长率从18.4%降至11%,而无预变形合金的抗拉强度为峰值强度的76.64%,伸长率从6.4%升至9.0%。预变形引入的位错提供S相形核位置,从而提高S相的形核率和合金力学性能。同时,位错作为1种能量陷阱,可降低S相在热暴露环境下的粗化速率,从而提高合金组织的热稳定性。

The effect of pre-deformation on micro-structural thermal-stability and mechanical properties of 2D12 alloy at elevated temperatures was investigated by means of tensile test and transmission electron microscopy（TEM）.The results showed that,by pre-stretching,the dispersity of S phase dramatically increased,and the effects of age hardening and the strength of 2D12 alloy from room temperature to 300 ℃ was promoted,while elongation after fracture decreases.Exposed at 200 ℃ for 500 h,the pre-stretched alloy retained its peak-aging tensile strength by 84.76,which is more than 76.64% for the alloy without pre-stretching,and the elongation of pre-stretched alloy decreases from 18.4% to 11.0%,while that of alloy without pre-stretching increaseed from 6.4% to 9.0%.It is indicated that the dislocation induced by pre-stretching provides nucleation sites for S phase,thus improves nucleation rate and mechanical properties of the alloy.Meanwhile,as a certain energy trap,the dislocation can decrease the coarsening rate of S phase when the alloy is exposed at elevated temperatures,thus improves the stability of the microstructure of the alloy.