挤压铸造Mg-Zn-Y合金显微组织与力学性能的研究

发布时间：2018-12-15 10:49

【摘要】：采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、万能拉伸试验机等手段,研究了不同挤压压力(0,50,100,150 MPa)对挤压铸造Mg_(93)Zn_6Y_1合金显微组织与力学性能的影响。结果表明:不同挤压压力下合金显微组织由基体α-Mg相和I-Mg_3YZn_6准晶相组成。α-Mg相呈枝晶状形态存在,分枝明显,I-Mg_3YZn_6准晶相以(I-Mg_3YZn_6+α-Mg)层片状共晶组织形态存在,呈网状分布在基体枝晶间。随着挤压压力的增大,α-Mg晶粒明显细化,层片状共晶组织变得细小,且由连续网状逐渐变为断裂网状,分布更均匀。合金的拉伸力学性能随着挤压压力的增大而逐渐提高,当挤压压力为150 MPa时,合金拉伸力学性能最优,其抗拉强度和伸长率分别为193 MPa和4.2%,增幅为30.4%和75.0%,合金力学性能的提高主要归因于细晶强化和I-Mg3YZn6相的强化作用。合金拉伸试样的断口形貌呈现准解理断裂特征。
[Abstract]:By means of optical microscope, (OM), scanning electron microscope, (SEM), X ray diffraction, (XRD), universal tensile testing machine, The effects of different extrusion pressures (050100150 MPa) on the microstructure and mechanical properties of squeeze casting Mg_ (93) Zn_6Y_1 alloy were studied. The results show that the microstructure of the alloy is composed of matrix 伪-Mg phase and I-Mg_3YZn_6 quasicrystalline phase under different extrusion pressures. 伪-Mg phase is dendritic and branched obviously. The I-Mg_3YZn_6 quasicrystals exist in the form of (I-Mg_3YZn_6 伪-Mg) lamellar eutectic structure, distributed in the interdendritic matrix. With the increase of extrusion pressure, the grain size of 伪-Mg is obviously refined, and the lamellar eutectic structure becomes fine, and gradually changes from continuous mesh to fracture mesh, and the distribution is more uniform. The tensile mechanical properties of the alloy increased gradually with the increase of extrusion pressure. When the extrusion pressure was 150 MPa, the tensile mechanical properties of the alloy were the best. The tensile strength and elongation of the alloy were 193 MPa and 4.2%, respectively. The increase of 30.4% and 75.0%, the improvement of the mechanical properties of the alloy is mainly attributed to the fine grain strengthening and the strengthening effect of I-Mg3YZn6 phase. The fracture morphology of the alloy tensile specimen shows the characteristics of quasi-cleavage fracture.
【作者单位】：中北大学材料科学与工程学院;
【基金】：科技部国际科技合作项目(2014DFA50320) 国家自然科学基金(51204147;51274175) 山西省国际科技合作项目(20130810172012081013) 山西省研究生教育创新项目(2015SY51)
【分类号】：TG292;TG146.22

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