热处理对2195铝锂合金微观组织与力学性能的影响

Effect of heat treatments on microstructure and mechanicalproperties of 2195 Al-Li alloy

对T8态2195铝锂合金板材实施不同条件下的固溶处理(430、 450、 470、 490和510℃)以及时效处理(18、 24和36 h),通过室温拉伸试验对固溶和时效处理后合金的抗拉强度与伸长率进行测量,采用SEM、 XRD、 EBSD和TEM对拉伸断口及微观组织进行观察。结果表明:固溶处理后的应力-应变曲线存在锯齿流变现象,但时效处理后消失,推测其产生的原因是波特文-勒夏特利埃效应。固溶处理可以有效提升合金的塑性,而时效处理则提高了合金的强度。进一步分析固溶与时效过程中的微观组织变化发现, β′相不参与固溶与时效析出,时效处理后强度的增加源于θ′相和δ′相析出产生的沉淀强化及弥散强化作用。

2195 Al-Li alloy sheets at T8 state were treated by solution treatment(430,450,470,490 and 510℃)and aging treatment(18,24 and 36 h).The tensile strength and elongation of the alloys after solution and aging treatments were measured by tensile test at room temperature.The tensile fracture and microstructure were observed by SEM,XRD,EBSD and TEM.The results show that the sawtooth flow phenomenon exists in the stress-strain curves after solution treatment,but disappears after aging treatment,which is attributed to Porterin-Le Chatelier(PLC)effect.Solution treatment can effectively improve the plasticity of the alloy,and aging treatment can improve the strength of the alloy.Further analysis on microstructure changes during solution and aging processes shows thatβ′phase does not participate in solution and aging precipitation,and the increase of strength after aging treatment is due to precipitation strengthening and dispersion strengthening caused by precipitation ofθ′phase andδ′phase.