Al-5Ti-1B细化剂对ADC12铝合金铸态组织及性能影响

Influence of Al-5Ti-1B refiner on the as-cast structure and mechanical properties of ADC12 Al alloy

采用光学显微镜(OM)、扫描电镜(SEM)及力学性能测试等手段研究了Al-5Ti-lB细化剂对ADC12铝合金的显微组织及力学性能的影响。结果表明:当Al-5Ti-l B加人量(质量分数,下同)小于0.2%时,初生ct-Al枝晶发达且粗大、是典型的树枝状;当加入0.2%的A1-5TMB时,合金铸态的晶粒细化效果最佳,a-Al枝晶细小均匀,常温抗拉强度提高40.2%,伸长率提高87.5%;而当细化剂加人量超过0.2%时,铸态晶粒细化效果衰退。分析表明金属间化合物1^2和TiAl3共存于铝合金熔体中时可共同成为有效的异质形核核心,促使晶粒细化。

The influence of Al-5Ti-lB refiner on the microstructure and mechanical properties of ADC 12 Al alloy has been studied using the optical microscope(OM),the scanning electron microscope(SEM)and the mechanical properties test.It is found that the primary a-Al dendrite is highly developed and thick,forming a typical dendrite morphology when the addition of Al-5Ti-lB is less than 0.2%mass fraction.The microstructure of ADC12 Al alloy is refined remarkably with optimum effect as adding 0.2%mass fraction of Al-5Ti-lB,which can improve the tensile strength by 40.2%and elongation by 87.5%.However,when the addition of Al-5Ti-lB is over 0.2%mass fraction,the refiner efficiency declines.The analysis shows that the intermetallic compounds TiB2 and Al3Ti can serve as the effective heterogeneous nucleation core when coexisting in the Al alloy melt and promote grain rofinement.