Ductilizing Mo-La2O3 alloys with ZrB2 addition
Ductilizing Mo-La2O3 alloys with ZrB2 addition
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添加 ZrB2 的球化 Mo-La2O3 合金
DOI：
10.1016/j.msea.2014.09.086
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发表时间：
2014
期刊：
影响因子：
6.4
通讯作者：
Sun J.
中科院分区：
文献类型：
--
作者：
Cheng P. M.;Li S. L.;Zhang G. J.;Zhang J. Y.;Liu G.;Sun J.
采用固-固混合/掺杂法制备了Mo-0.6wt%La2O3-xZrB 2（x=0，0.5，1.0，1.5，2.0wt%）合金。通过对显微组织、拉伸强度和塑性的实验研究，探讨了ZrB 2的加入对合金力学性能的影响。显微组织观察表明，添加0.5- 1.5wt%的ZrB 2可有效地减小合金的晶粒尺寸，并显著改变晶界第二相颗粒的分布。当ZrB 2的添加量为1.5wt%时，随着ZrB 2添加量的增加，晶间La 2 O3颗粒的尺寸逐渐减小。ZrB 2与氧反应生成的ZrO 2颗粒主要分布在晶界处，晶界处氧浓度降低，晶界处第二相颗粒体积分数增加。拉伸试验结果表明，合金的屈服强度对ZrB 2的加入相对不敏感，这与ZrB 2的强化机制有关。然而，延展性强烈依赖于添加剂。特别是，1.5wt%ZrB2掺杂的合金表现出显着的延展性增加超过40%时，与无ZrB 2的Mo-La 2 O3合金相比，虽然这两种合金具有相同的屈服强度水平。塑性化主要与反应添加产生的GB净化作用有关，它弥补了晶间相对塑性的削弱作用。本工作的发现提供了一种可能的方法来修改晶界，从而改善BCC合金的延展性，如在目前的钼合金。
Mo–0.6 wt%La2O3–xZrB2(x=0, 0.5, 1.0, 1.5, 2.0 wt%) alloys were prepared by using the solid–solid mixing/doping method. Microstructure, tensile strength, and ductility were experimentally examined to investigate the effect of ZrB2addition. Microstructural observations showed that the addition of 0.5–1.5 wt% ZrB2effectively reduces the grain size of the alloys and remarkably varies the second phase particles distributed at grain boundaries (GBs). The size of intergranular La2O3particles was decreased with the increasing ZrB2addition up to 1.5 wt%. ZrO2particles were produced through reaction between ZrB2and oxygen, which were predominantly distributed at GBs, increasing the volume fraction of intergranular second phase particles while decreasing the oxygen concentration at GBs. Tensile testing results displayed that the yield strength of alloys was relatively insensitive to the ZrB2addition, which was quantitatively understood with respect to the strengthening mechanisms. The ductility, however, was strongly dependent on the additions. In particular, the 1.5 wt% ZrB2-doped alloy exhibited a striking ductility increased by over 40% when compared with the ZrB2-free Mo–La2O3alloy, although the two alloys have the same level in yield strength. The ductilization is mainly related to the GB purifying effect derived from the reaction addition, which overwhelms the weakening effect of intergranular particles on ductility. The findings in the current work provide a possible approach to modify the GBs and hence to improve the ductility of BCC alloys such as in present Mo alloys.