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Phase boundary sliding of a reticular-structured Mg-O-9Al alloy
Journal of Alloys and Compounds ( IF 5.8 ) Pub Date : 2018-04-06
S.W. Kang, H. Kang, H.J. Choi, D.H. Bae

In a Mg-9Al alloy containing O atoms (Mg-O-9Al alloy) supplied from the decomposition of TiO2 nanoparticles in a Mg-9Al melt, the O atoms are mostly located in the eutectic β-phase after solidification. During homogenization treatment, the β-phase decomposes and the α′′-phase (hard) surrounded by thick α′-phase (soft) gradually develops by the spinodal decomposition of the homogenized α-phase. That is, when the compositions of both Al and O atoms are reached at near 5 at% in the α-phase, the spinodal decomposition activates in the range of the homogenization temperatures. The core-mantle structured (i.e., reticular-structured) Mg-O-9Al alloy shows high hardness and elastic modulus, and yield stress of 129 MPa and elongation to failure of 15.7%, much higher than those obtained in the homogenized Mg-9Al alloy (87 MPa and 8.7%). Because the hard α′′-phase is wrapped by the soft α′-phase, the α′′-phase undergoes phase boundary sliding during plastic deformation at room and high temperatures, exhibiting the α′′-phase rotation and shear deformation of the α′-phase. The alloy shows a strain rate sensitivity in the range of 0 (dislocation activity) to 1 (diffusion flow), depending on the plastic deformation mechanism of the α′-phase.



中文翻译:

网状结构的Mg-O-9Al合金的相界滑动

在由TiO 2分解提供的含有O原子的Mg-9Al合金中(Mg-O-9Al合金)在Mg-9Al熔体中的纳米颗粒中,固化后O原子大部分位于共晶β相中。在均质化处理中,通过均质化的α相的旋节线分解,β相分解,被厚的α′相(软质)包围的α′′相(硬质)逐渐发展。即,当在α相中Al和O原子的组成都达到接近5at%时,在均质温度范围内,旋节线分解活化。芯幔结构(即网状结构)Mg-O-9Al合金具有较高的硬度和弹性模量,屈服应力为129 MPa,断裂伸长率为15.7%,远高于均质的Mg-9Al合金(87 MPa和8.7%)。因为硬α'相被软α'相包裹,在室温和高温下的塑性变形过程中,α′相经历相边界滑动,表现出α′相的旋转和剪切变形。根据α'相的塑性变形机理,该合金的应变率灵敏度在0(位错活性)至1(扩散流)的范围内。

更新日期:2018-04-07
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