摘要伴随着现代工业的快速发展，振动和噪音带来的危害日益严重。因此，高阻尼性能材料的需求增多。近年来，镁合金材料因其高阻尼、低密度、高强度的特点而得到了广泛关注。本文通过改变铸态Mg-Zn-Y-Zr合金中合金元素Zr的含量，研究Zr含量变化对Mg-Zn-Y-Zr合金组织、力学性能和阻尼性能的影响。86749

本文所设计的Mg-Zn-Y-Zr合金为Mg-2。5Zn-5Y-xZr，x分别为0。5wt%、1。0wt%、1。5wt%和2。0wt%。通过不同Zr含量铸态合金之间的对比，研究铸态合金的组织和性能随Zr含量变化而变化的规律。实验采用了ZEISS光学显微镜、SEM和XRD等仪器和手段来分析合金的显微组织和相组成，并测定合金的室温显微维氏硬度（HV）、室温拉伸性能以及应变阻尼性能。

研究结论显示，铸态Mg-2。5Zn-5Y-xZr合金的微观组织主要由α-Mg基体、X相（Mg12YZn）和微量的W相（Mg3Y2Zn3）组成。随着Zr含量的增大，合金晶粒尺寸得以细化，合金中第二相的析出量增多，细晶强化和第二相强化的共同作用使铸态合金的力学性能得以提高，其中Mg-2。5Zn-5Y-2。0Zr合金的力学性能指标达到最大，其抗拉强度，屈服强度和延伸率分别为211。79MPa、77。86MPa和10。0%，其显微硬度值和其他合金相比，也达到最大值，为76。31HV。合金高温阻尼性能是位错阻尼机制和晶界阻尼机制共同作用。综合得出，Mg-2。5Zn-5Y-1。5Zr镁合金的阻尼性能最好。

毕业论文关键词：Mg-2。5Zn-5Y-xZr；微观组织；力学性能；阻尼性能

Abstract The harm caused by vibration and noise is more and more serious with the rapid development of modern industry。 Therefore, the demand of high-damping material is increased。 In recent years, magnesium alloy has been widely concerned because of its high damping, low density and high strength。 In this paper, the influence of Zr content on microstructure, mechanical properties and damping properties of Mg-Zn-Y-Zr alloy was studied by changing the content of Zr in the as-cast Mg-Zn-Y-Zr alloy。

The Mg-Zn-Y-Zr alloy designed in this paper is Mg-2。5Zn-5Y-xZr,and X is 0。5wt。%, 1。0wt。%, 1。5wt。% and 2。0wt。% respectively。 The law of the variation in the microstructure and properties of as-cast alloys with the change of Zr content were studied, by the comparison of as-cast alloys with different Zr content。 Microstructure and phase composition of the alloys was analyzed by ZEISS optical microscope , SEM and XRD,the microhardness (HV) and tensile properties at room temperature and strain damping properties of the alloys were also measured。

The results show that the microstructure of as-cast Mg-2。5Zn-5Y-xZr alloy is mainly composed of α-Mg matrix, X-phase (Mg12YZn) and tiny W-phase (Mg3Y2Zn3)。 With the increase of Zr content, the grain size of the alloy can be refined, and the precipitation of the second phase in the alloy is increased, the mechanical properties of as-cast alloy were improved by the joint action of fine grain strengthening and second phase strengthening。 The mechanical properties of the Mg-2。5Zn-5Y-2。0Zr alloy reaches the maximum,its tensile strength, yield strength and elongation were 211。79MPa, 77。86MPa and 10%, respectively。 Compared with other alloys, the microhardness of the Mg-2。5Zn-5Y-2。0Zr alloy also reached the maximum, which was 76。31HV。 The high-temperature damping capacity of the alloy is the interaction of the dislocation damping mechanism and the grain boundary damping mechanism。It is found that the damping properties of Mg-2。5Zn-5Y-1。5Zr magnesium alloy are the best。

Keywords: Mg-2。5Zn-5Y-xZr alloys; microstructure; mechanical property; damping property

目录

第一章  绪论 1

1。1 选题的背景及意义 1