摘要
利用粉末冶金法制备了含15%SiC(体积分数)的SiC/Al-7.5Zn-2.8Mg-1.7Cu(质量分数,%)复合材料及其合金,对比了复合材料及其合金的硬度、电导率和力学性能随时效时间延长的变化规律,并提出了适用于SiC/Al-Zn-Mg-Cu复合材料的T6时效热处理工艺。利用TEM和HRTEM技术,对不同时效状态下的纳米析出相进行了定量分析。结果表明,SiC颗粒对复合材料的时效过程具有明显的促进作用,相同人工时效工艺处理后,复合材料中析出相尺寸更大、密度更低。复合材料提前14 h达到硬度最大值(238 HV),且比未增强合金的硬度最大值高29 HV。复合材料晶界处无析出带(PFZ)宽度与未增强合金相似,但粗大的第二相明显增多,这些晶界相和界面反应产物的形成均可消耗合金元素,降低晶内沉淀相的密度。HRTEM结果表明,SiC颗粒没有改变Al-Zn-Mg-Cu合金的时效析出序列,仍为过饱和固溶体(SSS)-GP区-η'-η相,其中过渡相η'是T6态复合材料的主要强化相。
Particulate reinforced aluminum matrix composites are widely used in various industrial fields owing to their high specific strength and modulus,low coefficient of thermal expansion,etc.In general,because stronger matrix alloys tend to produce stronger composites,composites with high-strength Al-Zn-Mg-Cu alloys as the matrix are paid considerable attention.However,the aging behavior of the SiC/Al-Zn-Mg-Cu composites has not been well understood.In the present work,SiC particles with a vol-ume fraction of 15%reinforced Al-7.5Zn-2.8Mg-1.7Cu(mass fraction,%)composite and corresponding unreinforced alloy were fabricated using the powder metallurgy technique.The effects of the aging time on the hardness,electrical conductivity,and mechanical properties of the composite and corresponding matrix alloy were investigated.The T6 heat treatment process suitable for the composite was proposed.The nanoscale precipitates under different aging conditions were quantitatively analyzed using TEM and HRTEM.The results indicated that the SiC particles exhibited an obvious promoting effect on the aging process of the SiC/Al-Zn-Mg-Cu composite.The composite reached the corresponding maximum hardness 14 h earlier than the unreinforced alloy.The maximum hardness(238 HV)of the composite was 29 HV higher than that of the unreinforced alloy.The width of the precipitation-free zone of the composite was similar to that of the unreinforced alloy,but the number of the grain boundary phases in the composite increased.The formation of the grain boundary phases and interfacial reaction products could consume alloying elements and reduce the density of precipitated phases in the composite.Based on HRTEM,SiC particles did not change the aging precipitation sequence(SSS-GP zone-η'-η)of the Al-Zn-Mg-Cu alloy,and theη'phase was the major strengthening phase of the T6-treated SiC/Al-Zn-Mg-Cu composites.
作者
马国楠
朱士泽
王东
肖伯律
马宗义
MA Guonan;ZHU Shize;WANG Dong;XIAO Bolv;MA Zongyi(Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China 2 School of Materials Science and E;ngineering,University of Science and Technology of China,Shenyang 110016,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第12期1655-1664,共10页
Acta Metallurgica Sinica
基金
国家重点研发计划项目No.2017YFB0703104
国家自然科学基金项目No.51771193
辽宁省“兴辽英才计划”项目No.XLYC2007009。
关键词
粉末冶金
金属基复合材料
时效行为
析出相
力学性能
powder metallurgy
metal matrix composite
aging behavior
precipitated phase
mechanical property
