摘要
采用多道次搅拌摩擦加工的方法制备了高体积分数Cu颗粒增强7075铝合金的表面复合材料,利用电子背散射衍射(EBSD)、X射线衍射(XRD)、背散射电子成像和硬度测试等技术,结合蒙特卡洛模拟的方法,研究了复合材料制备过程中的流动行为及增强体分布规律。研究结果表明,道次数的增加能够细化Cu颗粒尺寸以及改善颗粒分布,同时有效促进原位反应的进行,形成Cu基固溶体和Al2Cu颗粒的双重增强体系。但是由于有效界面反应面积的减少,原位反应的速率在不断减缓并逐渐平稳,说明在采用多道次搅拌摩擦加工制备高体积分数原位复合材料时,很难实现增强体的完全溶解。通过分析多道次加工过程中Cu颗粒的位置演变和材料的块状流动规律,建立了流动模型。此外,为了定量研究Cu颗粒在Al基复合材料中的分布情况,采用一种改进的最近邻指数从试验和蒙特卡洛模拟两个角度对Cu颗粒分布的均匀性进行了分析,结果显示至少需要5个道次才能确保增强体的均匀性。
Al alloy surface metal matrix composites(SMMCs)are widely utilized as favorable structural materials in many industrial fields.The SMMCs on 7075 aluminum alloy reinforced by a high-volume fraction of Cu particles were prepared via multi-pass friction stir processing(FSP)in this work.The microstructure and microhardness of the SMMCs were investigated to reveal in-situ reaction and flow behavior.Besides,a material flow pattern during multi-pass FSP based on Cu particles distribution and material bulk flow direction were established.To determine a suitable processing pass,we introduced the nearest neighbor index(NNI)value which was based on microhardness distribution and metallography images to further quantify the distribution of reinforcement particles.This quantified parameter could be used as a response of the artificial neural network(ANN)system to optimize the sensitivity of the trained system to the reinforcement distribution to help achieve a more even distribution in subsequent experiments.First,the macroscopic metallographic structure of samples with different passes was observed to determine the evolution of SMMCs structure.Furthermore,the microstructures of different deformed regions were characterized by electron backscatter diffraction(EBSD),which revealed the grain’s orientation characteristics and bulk flow.Besides,X-ray diffraction(XRD)and energy dispersive spectrum(EDS)wereused to analyze the influence of processing passes on the Al-Cu in-situ reaction.The kinetic models of chemical reaction were used to quantitatively calculate the degree of in-situ reaction.A microhardness test was carried out on the MH-3 type digital microhardness tester.The hardness values of the whole cross section were measured with a lateral spacing of 0.5 mm and a longitudinal spacing of 1 mm.Meanwhile,Monte Carlo simulation was used to reconstruct the particle distribution.Through the observation of the microstructure,it could be found that the copper particles segregate seriously in the early stage of processing.As the
作者
朱禹龙
曹宇
黄光杰
张成行
李启磊
刘庆
Zhu Yulong;Cao Yu;Huang Guangjie;Zhang Chenghang;Li Qilei;Liu Qing(International Joint Laboratory of Light Alloys(MOE),College of Materials Science and Engineering,Chongqing Univer-sity,Chongqing,400044,China;Light Metal Materials Research Department,Shenyang National Research Center for Materials Science,Chongqing 400044,China;College of Materials Science and Engineering,Nanjing Tech Univer-sity,Nanjing 211816,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第12期1533-1545,共13页
Chinese Journal of Rare Metals
基金
中央高校基本科研业务费项目(2020CDJQY-A003)
国家自然科学基金创新研究群体项目(51421001)资助。
