Unraveling the effects of Zn addition and hot extrusion process on the microstructure and mechanical properties of as-cast Mg-2Al magnesium alloy
Unraveling the effects of Zn addition and hot extrusion process on the microstructure and mechanical properties of as-cast Mg-2Al magnesium alloy
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DOI：
10.1016/j.vacuum.2019.06.013
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发表时间：
2019-09-01
期刊：
影响因子：
4
通讯作者：
Emamy, Massoud
中科院分区：
文献类型：
--
作者：
Razzaghi, Marjan;Mirzadeh, Hamed;Emamy, Massoud
研究了Zn添加量和挤压热变形对Mg-2Al-xZn（x = 0，0.5，1，2，5 wt%）镁合金铸态组织和力学性能的影响。结果表明，同时添加2wt%Al和0.5wt%Zn（AZ 20合金）是一种有效的铸态细化α-Mg的方法，其拉伸性能显著提高，断裂机制由脆性解理面转变为以韧性韧窝为特征的纤维状形貌。进一步添加Zn对晶粒尺寸的影响可以忽略不计，但导致Mg-21（Zn，Al）（17）金属间化合物（称为φ相）的出现，其中后者由于其不利的形态而导致铸态铸锭的拉伸性能劣化。挤压后，组织沿着细化，再结晶，第二相颗粒破碎分散。除了Hall-Petch关系所证实的细晶粒尺寸的影响外，发现在ZA 52（Mg-5 Zn-2Al）合金中存在细分散的颗粒有利于提高挤压合金的力学性能和拉伸韧性。基于这些发现，建议在锻造条件下使用这些合金。
The effects of zinc addition and hot working via extrusion process on the microstructure and mechanical properties of as-cast Mg-2Al-xZn (x = 0, 0.5, 1, 2, and 5 wt%) magnesium alloys were studied. It was revealed that the simultaneous addition of 2 wt% Al and 0.5 wt% Zn (known as AZ20 alloy) is an effective way for refining of a-Mg in the as-cast condition, which resulted in a significant enhancement of tensile properties and changing the fracture mechanism from brittle cleavage facets to fibrous appearance characterized by ductile dimples. Further addition of Zn had negligible effect on the grain size but resulted in the appearance of Mg-21(Zn,Al)(17) intermetallic known as phi-phase, where the latter resulted in the deterioration of tensile properties of as-cast ingot due to its unfavorable morphology. After extrusion process, fine and recrystallized microstructures were observed along with the fractured and dispersed second phase particles. Besides the effect of fine grain size as verified by the Hall-Petch relationship, the presence of finely dispersed particles in the ZA52 (Mg-5Zn-2Al) alloy was found to be favorable in improving the mechanical properties and tensile toughness of the extruded alloy. Based on these findings, it was recommended to use these alloys in the wrought condition.