超声处理对稀土掺杂AM60B镁合金组织及力学性能的影响

发布时间：2018-11-15 16:02

【摘要】：在AM60B镁合金熔炼过程中加入混合稀土Y,Gd并辅以超声熔体处理工艺制备合金,利用光学显微镜(OM)、透射电镜(TEM)和万能试验机,研究了添加复合稀土和超声处理对镁合金微观组织和力学性能的影响,分析了其作用机制。结果表明,添加混合稀土Y,Gd后,未经超声处理的试样,稀土化合物存在于合金组织中,阻碍了位错和晶界滑移,α-Mg基体晶粒明显细化,β相减少,合金抗拉强度σ_b和延伸率δ分别达到257 MPa和9%,强度提高约20%。施加超声处理能进一步细化合金组织,使得α-Mg基体晶粒更加等轴细小,抑制β相在晶界处的连续网状分布。稀土相趋于弥散均匀分布,促进了稀土元素的细晶强化作用,使合金抗拉强度提高到269 MPa,延伸率达到11%。当稀土添加量超过一定范围后,稀土相开始粗化并割裂基体,这时超声处理对合金组织的改善作用有限,合金力学性能呈现下降的趋势。
[Abstract]:In the process of AM60B magnesium alloy melting, the alloy was prepared by adding the mixed rare earth YGd and ultrasonic melt treatment process. (OM), transmission electron microscope (TEM) and universal testing machine were used to prepare the alloy. The effect of adding complex rare earth and ultrasonic treatment on microstructure and mechanical properties of magnesium alloy was studied and its mechanism was analyzed. The results show that the rare earth compounds are present in the microstructure of the alloy without ultrasonic treatment, which hinders dislocation and grain boundary slip. The grain size of 伪-Mg matrix is obviously refined and the 尾-phase is decreased. The tensile strength 蟽 _ b and elongation 未 of the alloy reached 257 MPa and 9, respectively, and the strength increased about 20%. Ultrasonic treatment can further refine the microstructure of the alloy, make the 伪-Mg matrix grains more equiaxed and fine, and inhibit the continuous network distribution of 尾 phase at grain boundaries. The rare earth phase tends to distribute uniformly, which promotes the fine grain strengthening of rare earth elements, and increases the tensile strength of the alloy to the elongation of 269 MPa,. When the amount of rare earth was more than a certain range, the phase of rare earth began to coarsening and splitting the matrix, and the effect of ultrasonic treatment on the microstructure of the alloy was limited, and the mechanical properties of the alloy showed a downward trend.
【作者单位】：江汉大学机电与建筑工程学院;
【基金】：湖北省自然科学基金重点项目(20081385)资助
【分类号】：TG146.22

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