DC铸造Al-12Si-0.65Mg-xMn合金中第二相的形成  

Formation of Second-Phases in a Direct-Chill Casting Al-12Si-0.65Mg-xMn Alloy

作　　者：王光东 田妮 何长树[1,2] 赵刚 左良[2,3] WANG Guangdong;TIAN Ni;HE Changshu;ZHAO Gang;ZUO Liang(School of Materials Science ＆ Engineering,Northeastern University,Shenyang 110819,China;Key Laboratory for Anisotropy and Texture of Materials（Ministry of Education）,Northeastern University,Shenyang 110819,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]东北大学材料科学与工程学院,沈阳110819 [2]东北大学材料各向异性与织构教育部重点实验室,沈阳110819 [3]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2018年第7期1059-1067,共9页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51371045;国家重点研发计划项目Nos.2016YFB0300801和2016YFB1200506-12~~

摘　　要：采用LSCM、XRD、SEM、TEM及其附带的EDS,结合相图分析研究了半连续铸造(DC铸造)Al-12Si-0.65Mg-(0~2.27)Mn(质量分数,%)合金铸锭中的第二相及其形成过程。结果表明,Al-12Si-0.65Mg合金铸锭中存在α-Al、共晶Si、Mg_2Si和p相(Al_8Mg_3FeSi_6),它们分别是在567℃通过L+Al_5Fe Si→α-Al+Si+Al_8Mg_3FeSi_6、555℃通过L→α-Al+Si+Mg_2Si及550~554℃通过L→α-Al+Si+Mg_2Si+Al_8Mg_3FeSi_6反应形成的。当合金中添加Mn时,α-Al枝晶明显细化,同时合金铸锭中出现α-Al(FeMn)Si相;当Mn含量(质量分数,下同)从0.10%增加至2.27%时,α-Al枝晶形貌、尺寸及数量无明显变化,α-Al(FeMn)Si数量增多而尺寸不变;当Mn含量达到1.07%时,合金在647℃通过L+Al_6Mn→α-Al+Al_9Mn_4Si_3反应生成尺寸约80 mm的Al_9Mn_4Si_3,其中溶解了少量Fe形成Al_9(FeMn)_4Si_3,随Mn含量增加其数量增多而尺寸不变;经550℃均匀化处理后,合金中的Mg_2Si相溶入基体消失,共晶Si、p相和α-Al(FeMn)Si相球化成颗粒状,Al_9(FeMn)_4Si_3相形貌、尺寸及数量几乎不变,Al-12Si-0.65Mg-(0.10~2.27)Mn合金基体中析出尺寸约几百纳米的Al_9(MnFe)_2Si_3弥散相粒子,其数量随Mn含量增加而增多。Mg-containing high Si aluminum alloy that can be heat treatment enhanced is widely used in the fields of engine, vehicle industry and aerospace, because of its high specific strength, high wear resistance, corrosion resistance and low thermal expansion coefficient. At present, the alloying to improve the microstructure of Mg-containing high Si aluminum alloy and improve its mechanical properties is an important research hotspot of this kind of alloy. As an important alloying element in aluminum alloy, Manganese is of great significance to study the type and formation process of Mn-containing second phase in Mg-containing high Si aluminum alloy. The second phases and their formation in a direct-chill casting Al-12 Si-0.65 Mg-（0~2.27）Mn（mass fraction, %） alloy were investigated by LSCM, XRD, SEM/EDS and TEM/EDS, combined with phase graph analysis. The results show that there are eutectic silicon, Mg2 Si and p-（Al8 Mg3 FeSi6） besides matrix α-Al in the Mn-free Al-12 Si-0.65 Mg（mass fraction, %） alloy ingot, which are formed by the reactions of L＋Al5 Fe Si→α-Al＋Si＋Al8 Mg3 FeSi6, L→α-Al＋Si＋Mg2 Si and L→α-Al＋Si＋Mg2 Si＋Al8 Mg3 FeSi6 at 567, 555 and 550~554 ℃, respectively. The α-Al dendrites are obviously refined, and aAl（FeMn）Si phase can be observed with the addition of Mn to Al-12 Si-0.65 Mg-（0.10~2.27）Mn（mass fraction, %） alloy ingot. With the Mn content increasing from 0.10% to 2.27%, the morphology of α-Al dendrites has no obvious change, and the number of α-Al（FeMn）Si increases gradually whereas the size of α-Al（FeMn）Si doesn＇t change much. There are some Al9（FeMn）4 Si3 with the size of about 80 mm in the Al-12 Si-0.65 Mg-（1.07~2.27）Mn（mass fraction, %） alloy ingot with the Mn content over 1.07%, which are formed by the reaction of L＋Al6 Mn→α-Al＋Al9Mn4Si3 at 647 ℃, and Al9Mn4Si3 turns into Al9（FeMn）4 Si3 with Fe dissolved into it. The number of Al9（FeMn）4 Si3 increases with the Mn content increasing from 1.07% to2.2

关 键 词：含Mg共晶Al-Si合金 MN 第二相 DC铸造 均匀化 

分 类 号：TG146.2[一般工业技术—材料科学与工程]