亚共晶铝硅合金锶变质处理的孕育和衰退

通过考察A356合金变质后在静置和重熔过程中细化效果的变化,分析研究了亚共晶铝硅合金变质处理的孕育和衰退,以及合金锭预变质对变质效果的影响.结果表明,变质衰退表现为Sr含量低于某一临界值,有效期取决于初始Sr含量、熔化工艺及精炼方法等;变质处理孕育期的直接成因是中间合金释放Sr元素并与Si晶胚达到吸附平衡需要一定的时间;采用预变质合金锭,能够消除变质处理孕育期,稳定变质效果.

Incubation and Fading of Sr Modification in Hypoeutectic Al-Si Alloys

By investigating systematically the change of modification effects during holding and remelting of A356 Alloy,incubation and fading of Sr modification are analyzed,as well as the effect of modified ingot on modification process.It is showed that fading of modification is due to Sr content less than some a critical value for melting loss,and effective period of modification is dependent on primary Sr content,melting process and refining process,etc;incubation period of Sr modification is related to the time of the dissolution of Al-10Sr master alloy,releasing of Sr atom,and absorption of Sr on Si crystal nucleus in melt;with modified ingot,incubation period is eliminated,and modification effect is stabilized.