The transformation of the platelike ? - alfesi to spherical a - alfesi during homogenization is markedly accelerated by the addition of minor mn and cr in al - mg - si alloy , as well as the recrystalization of alloys during hot extrusion has been inhibited , and ? " strengthening phase improved to precipitate in the process of aging 合金鑄錠均勻化處理過程中,形成含mn 、 cr的第二相al ( mnfe ) si和al ( mncrfe ) si等,這些顆粒加速長棒狀的b - alfesi相向尺度較小的粒狀的- alfesi相轉(zhuǎn)化,減少了粗大結(jié)晶相對(duì)合金性能的不利影響。