【摘要】 作为汽车关键承载部件，铝合金飞轮壳经热处理后，其力学性能可得到有效提升。采用X射线荧光光谱仪（XRF）、金相显微镜（OM）、扫描电子显微镜（SEM）、20 kN万能拉伸试验机、硬度计等对热处理前后的AlCu5Mn1Mg铝合金飞轮壳试验件的微观组织和力学性能变化规律进行了研究。结果表明，原始铸件的晶粒细小，组织致密，主要由大量形貌为蔷薇状和等轴状的α-Al晶粒和非平衡共晶相组成。当提高固溶温度后，晶界处的第二相粒子逐步溶解到铝基体中，但是过高的固溶温度导致晶粒发生粗化，有晶粒合并的现象发生，降低了材料的力学性能。随着固溶时间的延长，晶界处的合金元素向晶粒内部扩散，同时晶粒尺寸增大。在180℃时效5 h后，拉伸曲线存在Portevin-Le Chatelier(PLC)效应。挤压铸造AlCu5Mn1Mg铝合金飞轮壳构件的最佳热处理工艺为：固溶495℃×10 h，时效140℃×5 h。更多还原

【Abstract】 As a key load-bearing component of automobiles,the mechanical properties of the aluminum alloy flywheel housing can be effectively improved by heat treatment.An X-ray fluorescence spectrometer(XRF),an optical microscope(OM),a scanning electron microscope(SEM),a 20 kN universal tensile testing machine,and a hardness tester were used to investigate the changes of micro structure and mechanical properties of AlCu5Mn1 Mg aluminum alloy flywheel housing before and after heat treatment.The results show that the as-cast sample has fine,dense grains,and is mainly composed of a large number of α-Al with rosette and equiaxed morphologies and non-equilibrium eutectic phases.With the increase of solution temperature,the second-phase particles at the grain boundaries are gradually dissolved into the aluminum matrix.However,an excessively high solution temperature leads to grain coarsening and grain coalescence,which reduces the mechanical properties of the material.With the extension of solution time,the alloying elements at the grain boundaries diffuse into the interior of grains and distribute uniformly,and the grain size increases simultaneously.The Portevin-Le Chatelier(PLC) effect is observed in the tensile curve after aging at 180℃ for 5 h.The optimal heat treatment process for the squeeze-cast AlCu5MnlMg aluminum alloy flywheel housing component is determined as follows:solution treatment at 495℃ for 10 h followed by aging treatment at 140℃ for 5 h.更多还原