【作者】 高珊；

【导师】 王敬丰；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2010， 硕士

【摘要】 本文选择目前应用较为广泛的高阻尼MgZr镁合金,在其基础上逐步添加合金元素形成体系（MgZr、MgZnZr、MgZnZrY）,采用金相显微组织分析（OM）、X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、拉伸力学性能测试、动态机械分析（DMA）等实验手段研究了体系中各种合金经过常规变形工艺或热处理后其强度和阻尼性能的变化规律。本文首先介绍了近年来阻尼镁合金的研究背景及意义,总结了目前金属阻尼材料的表征、测量方法及形成机理,概述了目前阻尼镁合金的研究现状并提出了本论文的研究目的及意义。研究不同挤压工艺参数（T、ε）对Mg-Zr合金微观组织、屈服强度及阻尼性能的影响。通过引入Zener-Hollomon参数和数据拟合,建立了Z参数与合金再结晶平均晶粒度d之间的关系模型符合d=376.6 ? 13.6lnZ;得到挤压工艺参数与合金屈服强度之间的定量关系σ=100.9+296.5（376.6 - 13.6ln（εexp （Q/RT）））^1/2;得到挤压工艺参数与合金阻尼性能之间的定量关系Q_h^-1 = A（376.6 - 13.6 ln（εexp（Q/RT）））³ /εexp（-C₂/ε）。通过研究一次挤压、二次挤压、锻造三种塑形变形工艺以及不同热处理工艺（T4、T5、T6）对MgZnZr高强变形镁合金强度及阻尼性能的影响,发现变形工艺或热处理后,合金的各力学性能之间相差不多,但却使阻尼性能发生了显著变化。其中,变形工艺中锻造态ZK60镁合金的阻尼性能最好,相对于挤压态提高2倍多。热处理后,合金的阻尼性能均得到不同程度的提高,其中,固溶态合金的阻尼性能最好。几种工艺对MgZnZr合金阻尼性能的影响规律均可通过G-L理论很好解释。最后,研究主要针对MgZnZrY合金,分析添加不同含量的Y元素后,合金相析出的规律及对其微观组织、强度和阻尼性能的影响规律。研究发现:Y元素具有明显的细化晶粒的作用,并且Y、Zn原子的同时存在会引入长周期相、准晶相等。当Y/Zn比约为0.05-0.2时,合金中会生成准晶相（I相-Mg3Y6Zn）,当Y/Zn比大于0.5时,会有长周期相（X相-Mg12YZn-LPS）生成,而W相（Mg3Y2Zn3）会在Y/Zn为0.05-0.5的较大范围内存在。这几种相无论是对合金的强度还是阻尼性能均有所提高,其中贡献的大小依次为W+LPS>LPS>W+I>W>MgZn2。最后还发现,在综合性能最好的合金中,当W相与LPS结构共存时,其中的W相与Mg基体具有新的位相关系（[001]W//[01—10]α,（110）W//（0001）α）。更多还原

【Abstract】 In this thesis, the present widely used high damping MgZr magnesium alloys were chosen to form systems （MgZr、MgZnZr、MgZnZrY） through adding alloying element into them. The variation of strength and damping capacity of these alloy systems after general deformation and heat-treatment were systematically investigated by optical metallographic （OM）, X-ray diffraction （XRD）, scanning and transmission electron microscopy （SEM and TEM）, mechanical tensile properties test, dynamic mechanical analysis （DMA）.In the first part of the thesis, the background and significance of a recent progress of damping magnesium alloys was critically overviewed, which includes the token, test approach and damping forming mechanism. Based on investigation actuality, the objective and significance of this thesis were represented.In present study, the hot-extrusion deformation of conventional high damping Mg-Zr magnesium alloys was carried out by using a various processing parameter of temperature T and strain rateε, and the effect of deformation temperature and strain rate on microstructure, strength and damping capacities of Mg-Zr alloys have been investigated. By fitting , the quantitative relationship between extruded Zener-Hollomon（ Z =εexp（Q/RT）） parameter and grain size has been builded:d=376.6 - 13.6ln Z. The quantitative relationship between extruded parameter and the yield strength can expressed asσ=100.9+296.5（376.6 - 13.6ln（εexp （Q/RT）））^-1/2. The quantitative relationship between extruded parameter and the damping capacity can expressed as Q_h^-1 = A（376.6 - 13.6 ln（εexp（Q/RT）））³ /εexp（-C₂/ε） .The effect of series deformation processes （first extrusion, second extrusion and forging） and heat treatments on MgZnZr magnesium alloys was studied. We found that the mechanical properties of alloys after deformation process or heat treatment changed little, but the damping properties have obvious change for MgZnZr magnesium alloys in these different processes technology. The damping capacity of alloys treated by forging was increased more, and the damping properties in the forging state are more than twice than in the extrusion state. The damping properties have obvious increase for MgZnZr magnesium alloys in three different heat treatment technology, and the damping capacity of alloys treated by solution are increased more. The influences of processes technology on damping properties can be explained by the G-L theory. The high strength extruded MgZnZrY alloy was chosen to study the influence of Yttrium addition on microstructure, strength and damping capacity. In the light of present literature reports, Yttrium played significant role of the grain refinement, and the coexisting of Y, Zn atom will introduce long period structure and quasicrystalline phase. When the ratio of Y/Zn is 0.05-0.2, quasicrystalline phase（I phase-Mg3Y6Zn） formed. When the ratio of Y/Zn more than 0.5, long period structure （ X phase-Mg12YZn-LPS） formed. The W phase formed on a large scale of 0.05-0.5. These phases have both contribution on mechanical properties and damping capacities, and the contributions from big to small are: W+LPS>LPS>W+I>W. Also found in the end that in the best performance of the alloys, when W and LPS phases exist, the new phase relationships between W phase and Mg matrix formed（[001]W//[011—0]α,（110）W//（0001）α）.更多还原