铝镁包覆挤压材料界面微观组织与力学性能研究

发布时间：2018-07-10 13:20

本文选题：AZ镁合金 + 纯铝　；参考：《稀有金属》2015年06期

【摘要】：采用反向挤压技术将AZ31镁合金和纯铝材料在不同温度下挤压形成包覆棒材。挤压过程中纯铝包覆在镁合金外侧,镁铝间形成冶金结合界面,实现了镁铝双金属的复合。挤压完成后使用光学显微镜(OM)、扫描电子显微镜(SEM)及能谱(EDS)分析技术对镁铝包覆挤压合金进行了组织及力学性能分析,重点研究了铝镁合金结合界面处化学成分过渡及相结构的演化与分布,同时采用显微硬度计测试了镁铝结合界面的显微硬度。结果表明,通过反向热挤压工艺可以得到表面光洁、无明显缺陷的铝镁合金包覆挤压制品。在高温高压条件下,镁铝复合金属在界面结合区发生了元素扩散,铝镁合金浓度出现明显的梯度变化,进而在结合界面上发生冶金反应,形成约350μm厚的金属间化合物层,物相分析表明在靠近镁合金基体一侧生成富镁相Al12Mg17,靠近纯铝一侧生成富铝相Al3Mg2,主要为脆性相生成。沿包覆棒材横截面直径方向从边部到芯部进行显微硬度测试,结果表明,该合金包覆型材具有明显的力学不均匀性,在铝镁结合界面处的硬度高于两侧基体材料,其峰值硬度可达HV 200以上,包覆型材在结合界面的组织差异和强度、硬度失配导致结合界面的力学性能急剧弱化,容易产生开裂。
[Abstract]:AZ31 magnesium alloy and pure aluminum alloy were extruded to form coated bar at different temperatures by reverse extrusion. During extrusion, pure aluminum was coated on the outside of magnesium alloy, and the metallurgical bonding interface was formed between magnesium and aluminum, thus the composite of magnesium and aluminum bimetallic was realized. The microstructure and mechanical properties of magnesia-aluminum-coated extruded alloy were analyzed by means of optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) after extrusion. The chemical composition transition and the evolution and distribution of phase structure at the interface of Al-Mg alloy were studied. The microhardness of the interface was measured by microhardness meter. The results show that aluminum magnesium alloy coated extrusion products with smooth surface and no obvious defects can be obtained by reverse hot extrusion process. Under the condition of high temperature and high pressure, the element diffusion occurs in the interface bonding zone, the concentration of Al-Mg alloy changes obviously, and then metallurgical reaction occurs at the interface, forming an intermetallic compound layer about 350 渭 m thick. Phase analysis shows that Al _ (12) mg _ (17) is formed near the base side of magnesium alloy, and Al _ (3) mg _ (2) is formed near the side of pure aluminum, which is mainly formed by brittle phase. The microhardness test was carried out along the cross section diameter of the coated bar from the edge to the core. The results show that the alloy coated profile has obvious mechanical inhomogeneity, and the hardness at the interface between aluminum and magnesium is higher than that at both sides. The peak hardness can reach HV200 or above. The microstructure and strength of the cladding profile at the interface are different. The mismatch of hardness leads to the sharp weakening of the mechanical properties of the interface and the cracking is easy to occur.
【作者单位】：兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室;
【基金】：甘肃省科技重大专项项目(1203GKDJ004) 甘肃省青年科技基金项目(1308RJYA046)资助
【分类号】：TG379;TB331

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