(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用光學(xué)顯微鏡和掃描電鏡等檢測手段研究噴射沉積Al-27%Si合金二次加熱的顯微組織及其轉(zhuǎn)變規(guī)律。在二次加熱過程中，噴射沉積Al-27%Si合金的組織轉(zhuǎn)變經(jīng)歷3個階段：轉(zhuǎn)變初期，試樣中液相體積分數(shù)很少，Si相在晶界長大；轉(zhuǎn)變中期，試樣中液相體積分數(shù)不斷增大，α(Al)相與Si相熔化；轉(zhuǎn)變后期，α(Al)相消失，合金中Si相和液相兩相平衡，液相與Si相的體積分數(shù)不變，Si相尺寸卻隨之增大。二次加熱溫度越高，每個轉(zhuǎn)變階段的時間越短，隨著二次加熱的進行，合金中的Si相形貌逐漸由近球形轉(zhuǎn)變?yōu)榘鍡l形。
關(guān)鍵字: Al-27%Si合金；二次加熱；半固態(tài)成形；噴射沉積；α(Al)相；Si相
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The microstructures of spray-deposited Al-27%Si alloy and their evolutions at different re-heating temperatures were studied by optical microscopy (OM) and scanning electron microscopy (SEM). During the re-heating treatment of spray-deposited Al-27%Si alloy, Si phases coarsen at the grain boundaries, then the volume fraction of liquid phase increases with the re-melting of α(Al) phase and Si phase, and finally achieves the equilibrium of Si phase and liquid phase, the volume fractions of Si phase and liquid phase keep constant, but the dimension of Si phase increases with the decrease of Si particle number. With the temperature increase of the re-heating treatment, the transformation time of each transition stage decreases. The shapes of Si phases convert from near-spherical to the lamellae during the re-heating treatment.
Key words: Al-27%Si alloy; re-heating treatment; semi-solid forming; spray depositing; α(Al) phase; Si phase
