重熔工藝與組織演變
(東北大學(xué) 材料電磁過(guò)程研究教育部重點(diǎn)實(shí)驗(yàn)室，沈陽(yáng) 110004)
摘 要: 對(duì)在兩相區(qū)鑄造進(jìn)行半固態(tài)制漿所得AZ91D鎂合金坯料的部分重熔工藝條件及組織演變進(jìn)行了研究。結(jié)果表明： AZ91D鎂合金在兩相區(qū)溫度(585℃)靜置30min且在水冷鐵模中澆注的兩相區(qū)鑄造半固態(tài)坯料， 在575℃下保溫30~45min進(jìn)行部分重熔時(shí)， 其組織具有固相顆粒球化程度高、 顆粒細(xì)小且粒度均勻、有效液相體積分?jǐn)?shù)高等特點(diǎn)； 坯料組織演變初始化階段、 球化階段和集聚合并長(zhǎng)大等3階段部分相互重疊。 對(duì)特定原始半固態(tài)坯料， 改變部分重熔溫度， 可縮短重疊區(qū)， 擴(kuò)大球化區(qū)， 實(shí)現(xiàn)坯料重熔進(jìn)程及組織形態(tài)的優(yōu)化，從而增加工藝可控性和提高坯料的觸變性。
關(guān)鍵字: 鎂合金； 半固態(tài)漿料； 兩相區(qū)鑄造； 微觀組織
two-phase-region casting AZ91D semisolid slurry ingot
（Key Laboratory of Ministry of Education for Electromagnetic Processing of Materials，
Northeastern University， Shenyang 110004, China）
Abstract:The microstructure evolution and partially remelting processing of two-phase-region casting AZ91D magnesium alloy ingots were investigated. The result indicates that the semisolid feedstock cast by held at two-phase-region temperature (585℃) for 30min and then poured in water-cooled-iron mould, as is remelted at 575℃ for 30～45min, refining and homogeneous solid grains with higher spheroidization degree and higher effective liquid volume fraction can be obtained. The microstructure evolution stages of the feedstock include initial stage, spheroidizing stage, and grouping and merging stage, which partially overlap with each other. For the special original semisolid ingot, the spheroidizing stage can be enlarged and the overlap bands can be narrowed through varying remelting temperature, therefore, the optimum microstructure feature and remelting processing will be realized, which will be beneficial to improve the process controllability and the thixoforming property of feedstock.
Key words: magnesium alloy; semisolid slurry; two-phase-region casting; microstructure
