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首页> 外文期刊>Materials Science and Engineering >A comparative study on the effects of Gd, Y and La rare-earth elements on the microstructure and creep behavior of AZ81 Mg alloy
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A comparative study on the effects of Gd, Y and La rare-earth elements on the microstructure and creep behavior of AZ81 Mg alloy

机译：GD，Y和La稀土元素对AZ81mg合金微观结构和蠕变行为的比较研究

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Impression creep tests were performed to study the effects of separate additions of 1 wt% Gd, Y, and La rare-earth (RE) elements on the microstructure and creep characteristics of a cast AZ81 Mg alloy. Constant punching stresses in the range 200-700 MPa were applied to the specimens at temperatures in the range of 423-523 K. The results revealed that the RE-containing alloys had lower creep rates in comparison with the base AZ81 alloy, the effect which was more significant in the AZ81+lLa alloy. The enhanced creep resistance of the RE-containing alloys is a consequence of; (ⅰ) formation of Al_2Gd and Al_2Y particles with cubic morphologies, as well as Al_(11)La_3 particles with acicular-branched morphology, (ⅱ) reduction in volume fraction of the β-Mg_(17)Al_(12) phase, and (ⅲ) solid solution strengthening of Al in the Mg matrix. The studied alloys had stress exponents and activation energies in the range of 4.2-6.7 and 83-118 kJ/mol, respectively. The observed declining trend of creep-activation energy with increasing stress indicates the competition of two simultaneous mechanisms of lattice-and pipe-diffusion controlled dislocation climb. Dislocation climb controlled by dislocation pipe diffusion, and the climb of edge dislocations were found to be prevalent at high and low stresses, respectively.
机译：进行印模蠕变试验以研究单独添加1wt％Gd，Y和La稀土（RE）元素对铸造AZ81mg合金的微观结构和蠕变特性的影响。在200-700MPa范围内的恒定冲压应力在423-523k的温度下施加到样品。结果表明，与基础AZ81合金相比，含有含量的合金具有较低的蠕变速率，其效果在AZ81 + LLA合金中更重要。含有重新含合金的增强的抗蠕变性是一种; （Ⅰ）具有立方体形态的AL_2GD和Al_2Y颗粒，以及具有针状分支形态的Al_（11）La_3颗粒，（Ⅱ）减少β-Mg_（17）Al_（12）相的体积分数，和（Ⅲ）在Mg基质中加强Al的固溶体。所研究的合金的应力指数和活化能量在4.2-6.7和83-118 kJ / mol的范围内。观察到随着应力越来越大的蠕变激活能量的趋势表明了两个同时机制的格子和管道扩散控制位错爬升的竞争。通过位错管道扩散控制的脱位升降，并且发现边缘位错的爬出分别在高压和低应力下普遍。

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