摘要
基于中位粒径分别为76μm和14μm的粗细两种SiC颗粒,按不同配比设计6种颗粒级配方案,并通过热等静压烧结成型制备体积分数为55%的SiC_(P)/2024Al复合材料,设计“冷热循环”和“固溶+冷热循环”两种稳定化热处理工艺,研究了颗粒级配及热处理对55%SiC_(P)/2024Al复合材料微观组织结构及尺寸稳定性的影响。结果表明:颗粒级配对铝合金基体中的Al_(2)Cu相含量有显著影响,当细SiC颗粒占比为40%时有利于Al_(2)Cu相的析出,而固溶+冷热循环稳定化热处理提高了Al_(2)Cu相的尺寸均匀性和分布均匀性,进一步提高相稳定性;在真实模型及标准模型中,稳定化热处理过程所产生的热错配应力水平,随着细SiC颗粒占比的提高表现出先上升后下降的趋势,占比为40%时Mises应力达到最大值(分别为7.95 MPa和3.52 MPa),有利于复合材料内部残余应力的释放,提高应力状态稳定性;采用14μm细SiC颗粒占比为40%的颗粒级配方案并进行固溶+冷热循环稳定化热处理时,55%SiC_(P)/2024Al复合材料具有最佳的尺寸稳定性,在5次180℃热载荷测试中的尺寸变化率保持在±0.07%以内。
Based on two kinds of SiC particles with the median particle size of 76μm and 14μm,six SiC particle grading schemes are designed according to different proportions,and the SiC_(P)/2024Al composites with 55%volume fraction are prepared by hot isostatic pressing sintering,and then two kinds of stabilization heat treatment strategies,which are“thermal-cold cycle”and“solid solution+thermal-cold cycle”,are designe.The effects of particle grading and heat treatment on the microstructure and dimensional stability of 55%SiC_(P)/2024Al composites are studied.The results show that the particle grading has a significant effect on the content of Al_(2)Cu phases in the aluminum alloy matrix.When the proportion of small SiC particles is 40%,it is conducive to the precipitation of Al_(2)Cu phases.The solid solution+thermal-cold cycle stabilization heat treatment improves the size and distribution uniformity of Al_(2)Cu phases and the phase stability.In the real and standard models,the thermal mismatch stress level generated by the stabilization heat treatment process shows a trend of first increasing and then decreasing with the increase of the proportion of fine SiC particles.Furthermore,the Mises stress reaches the maximum value(7.95 MPa and 3.52 MPa,respectively)when the proportion is 40%,which is conducive to releasing of the residual stress in the composites and improving the stability of the stress state.After adopting the particle grading scheme of small particle SiC accounting for 40%and carrying out the stabilization heat treatment of“solid solution+thermal-cold cycle”,55%SiC_(P)/2024Al composite has the best dimensional stability,with dimensional change rate remaining within±0.07%for 5 cycles thermal load at 180℃.
作者
崔岩
吕雪榕
蔡长宏
杨越
曹雷刚
CUI Yan;LYU Xuerong;CAI Changhong;YANG Yue;CAO Leigang(School of Mechanical and Materials Engineering,North China University of Technology,Beijing 100144,China)
出处
《材料工程》
北大核心
2025年第6期162-171,共10页
Journal of Materials Engineering
基金
国家重点研发计划(2022YFB3705702)。
