The effect of the 18R-LPSO phase on the fatigue behavior of extruded Mg/LPSO two-phase alloy through a comparative experimental-numerical study
The effect of the 18R-LPSO phase on the fatigue behavior of extruded Mg/LPSO two-phase alloy through a comparative experimental-numerical study
复制标题
DOI：
10.1016/j.jma.2020.07.005
复制
发表时间：
2021-01-15
影响因子：
17.6
通讯作者：
Enoki, Manabu
中科院分区：
文献类型：
--
作者：
Briffod, Fabien;Shiraiwa, Takayuki;Enoki, Manabu
通过实验和晶体塑性有限元模拟相结合的对比研究，研究了4种不同体积分数长周期堆积有序(LPSO)晶的挤压镁Y锌合金的疲劳行为。在不同的应变幅值下进行了应变控制的低周疲劳试验，结果表明，在不同的应变幅值下，镁合金的循环硬化是有限的，而镁99.2锌0.2Y0.6和镁97锌1Y2合金是软化的。随着LPSO相体积分数的增加，疲劳寿命随塑性应变的降低而降低，这与挤压LPSO颗粒塑性有限有关。利用应力-应变滞后曲线对考虑孪晶和去孪晶的晶体塑性模型进行了标定和验证。在应变控制条件下，分析了不同相间的相互作用对局部细观力学场在晶界分布的影响。形变孪晶活动在粗大的未再结晶晶粒中被预测，并随着LPSO相体积分数的增加而趋于消失。在LPSO晶体中观察到的解理类小平面与较高的拉应力有关，特别是在Mg/LPSO界面，这是因为LPSO晶体中适应基面外应变的变形机制有限。随着LPSO相体积分数的增加，疲劳极限的提高最终与挤压过程中较高的动态再结晶活性导致粗大的未再结晶α-Mg颗粒的减少有关。(C)2020年，爱思唯尔公司代表重庆大学出版。
The fatigue behavior of four extruded Mg-Y-Zn alloys containing different volume fractions of long-period stacking ordered (LPSO) grains was investigated through a comparative study combining experiments and crystal plasticity finite element simulations. Strain controlled low-cycle fatigue experiments were conducted at different strain amplitudes and revealed a limited cyclic hardening in Mg89Zn4Y7 alloy or softening in Mg99.2Zn0.2Y0.6 and Mg97Zn1Y2 alloys. A decrease in the fatigue life against the plastic strain with the increase in LPSO phase volume fraction was observed and was related the limited ductility of extruded LPSO grains. Stress-strain hysteresis curves were used to calibrate and validate a crystal plasticity model taking into account twinning and detwinning. The interaction of the different phases on the distribution of local micro-mechanical fields at the grain scale was then analyzed on synthetic microstructures under strain-controlled conditions. Deformation twinning activity was predicted in coarse unrecrystallized grains and tended to disappear with the increase in the LPSO phase volume fraction. Cleavage-like facets observed in LPSO grains were related to high tensile stress, especially at the Mg/LPSO interface, due to the limited number of deformation mechanisms in LPSO crystal to accommodate out-of-basal plane strain. The increase of the fatigue limit with the increase in LPSO phase volume fraction was finally associated with the decreasing presence of coarse unrecrystallized alpha-Mg grains due to a higher dynamic recrystallization activity during the extrusion process. (C) 2020 Published by Elsevier B.V. on behalf of Chongqing University.