时效前的预变形对喷射成形2195铝锂合金组织与性能的影响

Effect of pre-stretch on microstructure and properties of 2195 Al-Li alloy prepared by spray forming

研究了时效前的预拉伸变形量对喷射成形2195铝锂合金时效析出行为及力学性能的影响规律。结果表明:2195合金经固溶处理后直接时效,组织以δ′(Al_(3)Li)相+少量T1(Al_(2)CuLi)相为主,晶界处分布着大量断续分布的颗粒析出相组织(富AlCu相及AlCuFe相)。时效前的预拉伸变形在合金基体中引入的大量位错成为T1相、θ′相的有效形核点,显著促进T1相和θ′相晶内均匀、细小弥散析出,并降低晶界无析出带宽度,形成以T1、δ′相、θ′相为主的混合析出相组织。力学性能测试结果表明:当热处理工艺为(510℃,2 h)固溶处理+3%预拉伸+(155℃,24 h)时效处理,喷射成形2195铝锂合金室温抗拉强度约为(663±1)MPa,屈服强度约为(647±1)MPa,伸长率为(10.4±0.6)%,能够获得良好的强韧性匹配。

The effect of pre-stretch on the precipitation behavior and the mechanical properties of spray formed 2195 Al-Li alloy were studied.The results shows that lots ofδ′(Al_(3)Li)+less amount of T1(Al_(2)CuTi)phases can be observed in the microstructure of 2195 alloy after solution and aging treatment,accompany with many discontinuous grain precipitates.The dislocations increase significantly in the 2195 alloy with the introduction of pre-stretching deformation before aging treatment,which can act as effective nucleation sites of T1 andθ′phase causing T1 andθ′phase size decreasing and uniform dispersion.Meanwhile,the microstructure has a mixed precipitate,such as T1,δ′andθ′phase,and with PFZ decreasing.The results of mechanical properties showed that 2195 Al-Li alloy will have a good balance between the strength and toughness under the heat treatment of(510℃,2 h)solid solution+3%pre-stretching+(155℃,24 h)aging treatment.A good balance between strength and plasticity can be reached with the tensile strength of(663±1)MPa,the yield strength of(647±1)MPa and the elongation of(10.4±0.6)%.