Al-20％Si中间合金对Al-Si合金共晶Si变质行为的影响

摘要

The study was carried out to investigate the modification efficiency of AI-20%Si master alloy on Al-Si alloy. The experiment results show that by adding 1% AI-20%Si master alloy into the melt of Al-Si alloy, the eutectic silicon of AI-7%Si alloy can be modified from coarse-faceted silicon particles to fine fibrous or dot-like silicon, but the modification efficiency on eutectic AI-12%Si alloy is unsatisfactory. The pouring temperature has significant effect on the microstructure of Al-Si alloy. The microstructure of casting can be effectively refined by decreasing the pouring temperature appropriately. Lower modification temperature is beneficial to nucleation of silicon particles, and to suppression of the growth of dendrite structure. At 650 ℃, the effective modification time of AI-20% Si master alloy on AI-7%Si alloy is about 3 h.%研究了Al-20％Si中间合金对铸造Al-Si合金显微组织的影响.结果表明:向Al-Si合金熔体中加入1％的Al-20％Si中间合金,Al-7％Si合金中的共晶Si由粗大的板片状变为细密的纤维状或点状,变质效果较好,而对共晶Al- 12％Si合金的变质效果较弱；浇注温度对合金显微组织影响较大,适当降低浇注温度,有利于铸件组织的细化；变质温度越低越有利于颗粒状Si相成为形核核心,抑制枝晶组织的形成长大；在变质温度为650℃时,Al-20％Si中间合金对Al-7％Si合金变质有效时间是3h左右.