(1. 浙江大學(xué) 寧波理工學(xué)院，寧波 315100；2. 北京有色金屬研究總院，北京 100022)
摘 要: 采用橢圓旋扭管反復(fù)凝熔法制備半固態(tài)A356鋁合金漿料。結(jié)果表明：橢圓旋鈕管反復(fù)凝熔技術(shù)具有旋扭強(qiáng)制對(duì)流促進(jìn)初生晶核游離、自攪拌加強(qiáng)熔體剪切、反復(fù)凝熔促進(jìn)形核的作用，可使初生α晶核演變?yōu)榍蛐位蚪蛐尉Я！E圓管長(zhǎng)短軸比、旋扭強(qiáng)度以及凝熔頻率對(duì)半固態(tài)漿料的微觀組織有顯著影響。隨著長(zhǎng)短軸比、旋扭強(qiáng)度和凝熔頻率的增大，晶粒細(xì)化和圓整效果顯著提高；但長(zhǎng)短軸比過大，容易堵塞流道；當(dāng)旋扭強(qiáng)度超過13.5 (°)/cm時(shí)，晶粒細(xì)化和圓整效果沒有明顯提高；當(dāng)凝熔頻率超過40 μm−1時(shí)，晶粒細(xì)化作用不再增強(qiáng)，圓整度反而降低。在橢圓長(zhǎng)短軸比為1.8׃1、旋扭強(qiáng)度為13.5 (°)/cm、凝熔頻率為40 μm−1的條件下可制得晶粒直徑細(xì)小、形狀圓整的半固態(tài)漿料。
關(guān)鍵字: A356鋁合金；橢圓旋鈕管；反復(fù)凝熔法；半固態(tài)；微觀組織
repeated heating-cooling method with elliptical-twisted tubes
（1. Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China;
2. Beijing General Research Institute for Nonferrous Metals, Beijing 100088, China）
Abstract:The semi-solid slurry of A356 aluminum alloy was prepared by the repeated heating-cooling method with the elliptical-twisted tubes. The results indicate that by the repeated heating-cooling method with elliptical-twisted tubes the microstructures of primary grains are transformed from dendritic or rosette-shaped to fine net-globular under the action of grains detachment due to the forced convection, shear caused by self-stirring and heterogeneous nucleation because of repeated heating/cooling. The axial ratio, twisting strength and heating-cooling frequency have significant influences on the microstructure of the semi-solid slurry. With the increase of axial ratio, twisting strength and heating-cooling frequency, the grain refinement and sphericity of particles have remarkable improvement. However, at the twisting strength over 13.5 (°)/cm and heating-cooling frequency over 40 μm−1, the grain refinement does not have a much improvement and the sphericity decreases on the contrary. At the axial ratio of 1.8:1, twisting strength of 13.5 (°)/cm and heating-cooling frequency of 40 μm−1, the favorable microstructure of semi-solid A356 aluminum alloy can be generated by the repeated heating-cooling method with the elliptical-twisted tubes.
Key words: A356 Al alloy; elliptical-twisted tube; repeated heating-cooling method; semi-solid; microstructure
