(1. 清華大學(xué) 材料學(xué)院，北京 100084；
2. 清華大學(xué) 先進(jìn)成形制造教育部重點實驗室，北京 100084；
3. 中國商飛上海飛機制造有限公司復(fù)合材料中心，上海 201324；
4. 北京科技大學(xué) 鋼鐵共性技術(shù)協(xié)同創(chuàng)新中心，北京 100083；
5. 上海航天精密機械研究所，上海 201600)
摘 要: 建立了可控冷卻速率的實驗方法、凝固過程測溫方案和合金內(nèi)部溫度推算方法，對Mg-6Gd-3Y-0.5Zr(質(zhì)量分?jǐn)?shù)，%)(GW63K)合金開展可控冷卻速率實驗，結(jié)合X射線斷層掃描技術(shù)、掃描電子顯微鏡和X射線能譜分析等實驗表征手段，表征可控冷速鎂合金的凝固組織形貌并獲取定量信息，研究了冷卻速率對GW63K合金凝固組織微觀形貌、定量信息的影響和變化規(guī)律。結(jié)果表明：在GW63K合金凝固組織中，共晶呈網(wǎng)絡(luò)狀分布在晶界處，形狀不規(guī)則的第二相呈島狀分布在共晶組織中；平均冷卻速率Rc在0.13~0.33 ℃/s范圍內(nèi)，隨著冷卻速率的增加，網(wǎng)狀共晶組織更密集、均勻和連續(xù)，第二相分布更均勻、尺寸更小，微觀溶質(zhì)偏析減小，第二相和共晶體積分?jǐn)?shù)均呈下降趨勢。
關(guān)鍵字: Mg-Gd-Y-Zr；可控冷卻速率；X射線斷層掃描技術(shù)
（1. School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China;
2. Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084, China;
3. COMAC Shanghai Aircraft Manufacturing Co., Ltd., Composites Center, Shanghai 201324, China;
4. Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China;
5. Shanghai Spaceflight Precision Machinery Institute, Shanghai 201600, China）
Abstract:An experimental method of preparing Mg-Gd-Y-Zr alloy solidified at controlled cooling rate, acquiring temperature-time data during the solidification process, and calculating the temperature inside the alloy was established. The experiments were carried out on Mg-6Gd-3Y-0.5Zr (mass fraction, %) (GW63K) alloys, and several GW63K alloy specimens cooled at different rates in the range of 0.13-0.33 ℃/s were prepared. The solidification microstructure and quantitative information of the GW63K alloys were characterized by using X-ray tomography technique and SEM. The effects of cooling rate on the microstructure and quantitative information were discussed. Besides, the quantitative relationships between cooling rate and volume fractions of the eutectics and secondary phase were proposed, respectively. The results show that the eutectics of GW63K alloy which distribute at the grain boundaries present network-like morphology, and the secondary phase with irregular morphology distributes in the eutectics. With the increase of cooling rate in the range of 0.13-0.33 ℃/s, the primary phase with six-fold symmetry is refined. The eutectic networks become denser, more homogeneous and continuous. The secondary phase distributed more dispersively, and the average size of secondary phase become lower. In addition, the volume fractions of eutectics and secondary phase reduce with increasing the cooling rate.
Key words: Mg-Gd-Y-Zr; controlled cooling rate; X-ray tomography technique
