Microstructure, microstructural stability and mechanical properties of sand-cast Mg-4Al-4RE alloy
Microstructure, microstructural stability and mechanical properties of sand-cast Mg-4Al-4RE alloy
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DOI：
10.1016/j.matchar.2013.06.001
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发表时间：
2013-09-01
影响因子：
4.7
通讯作者：
Litynska-Dobrzynska, Lidia
中科院分区：
文献类型：
--
作者：
Rzychon, Tomasz;Kielbus, Andrzej;Litynska-Dobrzynska, Lidia
本文介绍了砂铸镁铝稀土合金在175℃和250℃热处理3000h后的相组成和组织稳定性试验结果，并用光学显微镜、扫描电子显微镜和透射电子显微镜对组织进行了分析。用X射线衍射仪测定了其物相组成。Mg_4Al-4RE(AE44)合金的组织由粗大的α-Mg固溶体、Al(11)RE(3)相的针状析出物、Al2RE相和Al10RE2Mn7相的多面体析出物组成。在175℃下3000h热处理后，合金组织没有变化，而在250℃下退火后，Al11RE3相的析出物处于球化的初始阶段。砂型铸造AE44合金中金属间化合物相的粗晶结构和不利形态是由低凝固速率引起的，导致在室温和175℃下的蠕变抗力低达200℃，机械性能低。(C)2013 Elsevier Inc.保留所有权利。
This paper presents a methodology for assessing the phase composition and the results of structural stability tests of the sand-cast Mg-4Al-4RE alloy after annealing it at 175 and 250 degrees C for 3000 h. The microstructure was analyzed with optical, scanning electron, and transmission electron microscopy. The phase composition was determined with X-ray diffraction. The structure of the Mg4Al-4RE (AE44) alloy is composed of large grains of alpha-Mg solid solution, needle-shaped precipitates of the Al(11)RE(3)phase, polyhedral precipitates of the Al2RE phase and Al10RE2Mn7 phase. After annealing at 175 degrees C for 3000 h, no changes in the alloy structure are observed, whereas after annealing at 250 degrees C the precipitates of the Al11RE3 phase are found to be in the initial stages of spheroidization. The coarse-grained structure and unfavorable morphology of the intermetallic phases in the sand-cast AE44 alloy, which are caused by low solidification rates, result in low creep resistance up to 200 degrees C and low mechanical properties at ambient temperature and at 175 degrees C. (C) 2013 Elsevier Inc. All rights reserved.