(1. 蘭州理工大學(xué) 省部共建有色金屬先進(jìn)加工與再利用國家重點實驗室，蘭州 730050；
2. 蘭州理工大學(xué) 有色金屬合金及加工教育部重點實驗室，蘭州 730050)
摘 要: 研究等溫?zé)崽幚頊囟群捅貢r間對ZC61-0.3Cr鎂合金半固態(tài)組織演變的影響。結(jié)果表明：在等溫?zé)崽幚磉^程中，ZC61-0.3Cr合金中的原始樹枝晶組織能夠轉(zhuǎn)變?yōu)榘牍虘B(tài)非枝晶組織，得到均勻、圓整的球狀顆粒。隨著保溫溫度的升高，合金中的原始樹枝晶組織經(jīng)過初始粗化、組織分離和球化演變成半固態(tài)非枝晶組織；隨著保溫時間的延長，晶界處的(α-Mg+MgZn2+CuMgZn)共晶組織優(yōu)先熔化，合金中的大塊狀組織逐漸演變?yōu)榍驙罱M織；但是，保溫溫度過高或保溫時間過長，都會引起球狀顆粒的粗化長大。在粗化長大過程中，合并長大機制和Ostwald熟化機制同時存在，共同影響固相顆粒的形貌和尺寸大小。ZC61-0.3Cr鎂合金半固態(tài)成形所需的最佳工藝條件為(585 ℃, 30 min)；此條件下，其顆粒平均尺寸、形狀因子和固相率分別為43 μm、1.4和51%。
關(guān)鍵字: ZC61-0.3Cr鎂合金；半固態(tài)等溫?zé)崽幚恚环侵ЫM織；組織演變
（1. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Non-ferrous Metal Alloys and Processing, Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The effects of the isothermal heat-treatment temperature and holding time on semi-solid microstructural evolution of ZC61-0.3Cr magnesium alloy were investigated. The results indicate that the original dendritic microstructure in ZC61-0.3Cr alloy can be transformed into semi-solid non-dendritic microstructure and can obtain uniform and round spherical particles during the isothermal heat-treatment. With the increase of holding time, the eutectic microstructure (α-Mg+MgZn2+CuMgZn) at the grain boundaries is melted preferentially, the original dendritic microstructure in the alloy is turned into semi-solid non-dendritic microstructure by initial coarsening, microstructure separation and spheroidizing. As the holding time increases, the microstructure of alloy gradually changes from large block to spherality. However, the coarsening and growth of spherical particles would cause, when the holding temperature is too high or the holding time is too long. In the process of coarsening and growth, the mechanism of combining growth and Ostwald ripening coexist and together affect morphology and size of the solid phase particles. The optimum process condition for semi-solid forming of ZC61-0.3Cr magnesium alloy is (585 ℃, 30 min). Under this condition, the average particle size, shape factor and solid fraction are 43 μm, 1.4 and 51%, respectively.
Key words: ZC61-0.3Cr magnesium alloy; semi-solid isothermal heat treatment; non-dendritic microstructure; microstructural evolution
