微量钪在Al-Cu-Li-Zr合金中的存在形式和作用

Existing Form and Effect of Trace Sc on Microstructure and Property of Al-Cu-Li-Zr Alloy

通过显微组织观察和室温拉伸实验,研究了微量Sc在Al-Cu-Li-Zr合金中的存在形式和对合金微观组织和拉伸性能的影响。结果表明:微量Sc在Al-Cu-Li-Zr合金中主要以初生Al3(Sc,Zr)和次生Al3(Sc,Zr)两种形式存在。初生的Al3(Sc,Zr)是合金凝固过程中形成的,可成为有效的非均质形核中心,显著细化铸态晶粒组织,具有细晶强化和增塑作用;次生Al3(Sc,Zr)是合金在热加工过程中析出的,对位错和亚晶界起钉扎作用,稳定亚结构并有效抑制合金再结晶,具有亚结构强化和直接析出强化作用。因此,加入微量Sc的Al-Cu-Li-Zr合金的强度和塑性大大提高。

The existing form and effect of trace Sc addition on microstructure and tensile property of Al-Cu-Li-Zr alloy have been investigated by observation of microstructure and tensile test at room temperature.The results show that addition of trace Sc precipitates primary Al_3(Sc,Zr) particles during solidification of the alloy,eliminates the dendrite,causes obvious grain refinement;and precipitates secondary Al_3(Sc,Zr) particles in the heating process,which can pin dislocation and subgrain boundary,stabilize substructure as well as strongly restrain recrystallization of the alloy.The strengthening mechanisms of the alloy are considered as fine grain strengthening,secondly Al_3(Sc,Zr) particles dispersion strengthening,substructure strengthening.Therefore trace Sc can obvious improve the strength and elongation of Al-Cu-Li-Zr alloy.