Sc元素对ZL205A合金组织和力学性能的影响EI北大核心CSCD

利用金相显微镜、扫描电镜、透射电镜等手段,研究Sc含量对砂型铸造ZL205A合金的组织和力学性能的影响规律。结果表明,Sc含量低于0.12%(质量分数,下同),未发现晶粒细化效果;Sc含量为0.06%,热处理态的合金晶界出现残留颗粒状W(AlCuSc)相,随Sc含量增加,W相由颗粒状转变为连续条带状;ZL205A合金热处理后弥散析出少量Al 3(Zr x,Ti 1-x)相,添加Sc后弥散相转变为Al 3(Zr x,Ti y,Sc 1-x-y)相,弥散相的数量随Sc含量的增加而增加;由于弥散相数量的增加,Sc含量为0.06%时,合金的时效响应速率和硬度峰值均略有增加,合金的屈服强度提高了4%;Sc含量为0.12%时,晶界残留相增加,Cu在α(Al)中的浓度降低,θ′相密度明显降低,合金的时效响应速率、硬度峰值以及力学性能各项指标均大幅下降;ZL205A合金中添加0.06%的Sc,即可明显地抑制θ′相的长大。

Effect of Sc on microstructure and mechanical properties of ZL205A alloy

The microstructure and ageing precipitation behavior of ZL205A alloy with different addition of Sc were investigated by OM,SEM and TEM.The results show that the grain refinement effect of Sc(up to 0.12%,mass fraction,the same below)is not observed in ZL205A alloy;the residual particle W(AlCuSc)phase is formed after heat treatment when the Sc content is 0.06%,and transformed to strip-liked structure with the increase of Sc content in the grain interface;the dispersed phases Al 3(Zr x,Ti 1-x)in ZL205A alloy are transformed to Al 3(Zr x,Ti y,Sc 1-x-y),and the number of the dispersed phases increase with the increase of Sc content;when the Sc content is 0.06%,the ageing response,peak hardness increase slightly,and the yield strength increases by 4%;while the Sc content increases to 0.12%,the decrease of the solute concentration may reduce the number of theθ′phase due to the strip-liked W phase formed in the grain interface,which results in the dramatic decrease of the ageing response,peak hardness and mechanical properties;traces of Sc help to slow down the growth ofθ′phase during the over-aged stage.