硼对Al-20Si合金初晶硅的细化作用

Effects of B on Refining Primary Si Phase in Hypereutectic Al-Si Alloy

研究了B对过共晶Al-20Si合金中初晶Si的细化作用。结果表明,B对Al-20Si合金中初晶Si具有良好的细化作用。初晶Si尺寸先随B含量的增加而减小,当B含量为0.065%时初晶Si尺寸达到最小,之后,随B含量的增加而增大;添加微量的Ca和Mg可促进B对初晶Si的细化作用;C2Cl6精炼除气会削弱B对初晶Si的细化效果。B与Ca、Mg等元素能反应生成可作为Si异质核心的化合物可能是B具有细化初晶Si作用的原因。

Effects of B on refining primary Si phase in hypereutectic Al-Si alloy were observed by OM(optical microscope),SEM(scanning electron microscope).The results reveal that B exhibits excellent refinement on primary Si phase in Al-20Si alloy.Size of primary Si phase is firstly decreased and then increased with increasing in B content,in which the smallest primary Si size can be observed with 0.065% B content.Trace Ca and Mg addition can promote the refining effects of B on primary Si phase,while C2Cl6 treatment can weaken the refining effects of B.The compounds formed from the reaction of B with Al,Si and Ca or Mg,which can be served as the nucleation substrates for primary Si phase,may be responsible for the refining effects of B on the primary Si phase.