铝锌镁铜锆钪合金型材的组织和性能

Microstructure and Properties of a Al-Zn-Mg-Cu-Zr-Sc Alloy Profile

采用光学显微镜、扫描电镜、电子背散射衍射仪、透射电镜及拉伸试验机等手段,研究了新型铝锌镁铜锆钪合金经挤压变形及双级时效处理后型材的组织和性能。结果表明:该合金型材双级时效后的抗拉强度为540 MPa,屈服强度为507 MPa,伸长率为11.1%,电导率为41.7%IACS;添加微量元素钪后,合金型材在伸长率和电导率相当的情况下,抗拉强度和屈服强度分别提高了4.5%和4.7%;钪主要以Al3(Sc,Zr)相形式存在,Al3(Sc,Zr)相可以显著细化合金的晶粒和阻碍合金的回复再结晶行为,并且有效抑制晶界无析出带的出现和晶界沉淀相的粗化;另外,在合金中发现了由铝、铜和钪三种元素形成的W相。

The microstructure and properties of a new Al-Zn-Mg-Cu-Zr-Sc alloy profile after extruding and two-step aging were studied using optical microscopy( OM),scanning electron microscopy( SEM),electronic back-scattered diffraction technique( EBSD),transmission electron microscopy( TEM) and tensile test. The results show that after twostep aging treatment,the tensile strength,yield strength,elongation and electrical conductivity of the alloy were 540 MPa,507 MPa,11. 1% and 41. 7 % IACS,respectively. With the minor addition of Sc,the tensile strength and yield strength increased by 4. 5% and 4. 7%,and the elongation and electrical conductivity almost didn't change. Scandium existed as Al3( Sc,Zr) phase which can refine grain size of the alloy,effectively restrain the recrystallization behavior and the appearance of precipitate free zones along grain boundaries and coarsing of precipitates on the grain boundaries. In addition,a ternary W phase composed of elements Al,Cu and Sc was observed in the alloy.