摘要
采用Mg-11Y-5Gd-2Zn-0.5Zr镁合金重力铸造发动机活塞,确定了浇注温度、模具温度、热处理工艺等参数。对镁合金活塞本体的组织研究表明,原始铸态合金组织中有大量的第二相分布于晶界处,经过固溶和时效热处理,在晶界处析出大量的层片状析出相。在时效态,活塞裙部的硬度(HV)达到131.4;活塞顶部的高温抗拉强度大,在350℃时的抗拉强度为161.9MPa;在250℃、80MPa条件下经过100h镁合金活塞材料的蠕变变形量只有0.428%;Mg-11Y-5Gd-2Zn-0.5Zr镁合金活塞的密度为1.995g.cm-3,100℃时比热容为850J.kg-1.K-1,室温热导率为23W.m-1.K-1,20～100℃的线膨胀系数为25.6×10-6K-1。
Heat resistant Mg-RE (Mg-11Y-5Gd-2Zn-0.5Zr) alloy engine piston was produced by gravity casting,and the processing parameters,such as pouring temperature,preheating temperature of the mould and heat treatment conditions,were optimized.Meanwhile,the microstructure of alloy piston was observed by optical microscope,SEM (scanning electron microscope).The results reveal that there exist amounts of secondary phases distributed along grain boundary in as-cast microstructure,while amounts of lamellar phases are precipitated from grain boundary after solid solution and ageing treatment.The Vickers-hardness of aged alloy piston shirt reaches 131.4,and high temperature tensile strength of piston top exhibits excellent with 161.9MPa at 350℃.In addition,creep strain of piston top is only 0.428% at 250℃/80MPa for 100 hours.The density,specific heat capacity at 100℃,thermal conductivity at room temperature and linear expansion coefficient at 20～100℃ reach 1.995g/cm3,850J/(kg·K),23W/(m·K) and 25.6×10-6/K,respectively.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2010年第5期455-458,共4页
Special Casting & Nonferrous Alloys
基金
国家安全重大基础研究项目(6133001E)
国家高技术研究发展计划(863计划)重点资助项目(2009AA033501)
