Ce-La-Th合金高压相变的第一性原理计算

采用第一性原理计算对Ce_(0.8)La_(0.1)Th_(0.1)在高压下fcc-bct的结构相变、弹性性质及热力学性质进行了研究讨论.通过对计算结果的分析,发现了合金在压力下的相变规律,压强升高到31.6 GPa附近时fcc相开始向bct相转变,到34.9 GPa时bct相趋于稳定.对弹性模量的计算结果从另一角度反映了结构相变的信息.最后,利用准谐德拜模型对两种结构的高温高压热力学性质进行了理论预测.

Y对Ce-Cu-Al-Nb块体非晶力学性能和耐腐蚀性能的影响(英文)

研究了Ce69.5-xCu18Al1 1Nb1.5Yx(x=0,1,2,3)块体非晶的非晶形成能力、力学性能和耐腐蚀性能。结果表明:添加Y元素能够有效提高Ce-Cu-Al-Nb合金的非晶形成能力。其中,Ce67.5Cu18Al1 1Nb1.5Y2样品具有最佳的非晶形成能力,过冷液相区ΔTx=97 K,玻璃化转变温度Tg=349 K。在298 K进行压缩时,所有样品都表现出脆性断裂行为,断口形貌为典型的叶脉状花样。在363 K进行压缩时,所有样品都表现出明显的宏观塑性变形行为,当x=0~2时,可以观察到应力过冲现象。Ce67.5Cu18Al1 1Nb1.5Y2样品在塑性变形时,其流变应力最低,应变平台区最宽,有利于塑性加工。同时发现,添加Y可以改善Ce-Cu-Al-Nb合金的耐腐蚀性能,其中Ce67.5Cu18Al1 1Nb1.5Y2样品的耐腐蚀性能最佳。

Comparative studies on as-cast microstructures and mechanical properties between Mg-3Ce-1.2Mn-0.9Sc and Mg-3Ce-1.2Mn-1Zn magnesium alloys

The as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-3Ce-1.2Mn-1Zn magnesium alloys were investigated and compared. The results indicate that the Sc-containing alloy mainly consists of α-Mg, Mg12Ce and Mn2Sc phases, and the Zn-containing alloy is mainly composed of α-Mg and Mg12Ce phases. The morphologies of the Mg12Ce phases in the two as-cast alloys are different. The Mg12Ce phases in the Sc- and Zn-containing alloys mainly exhibit particle-like shapes and continuous and/or quasti-continuous nets, respectively. Furthermore, the grains of the Sc-containing alloy are finer than those of the Zn-containing alloy. In addition, the Sc- and Zn-containing alloys have similar as-cast tensile properties at room temperature and 300 °C. However, the Sc-containing alloy exhibits higher creep-resistant properties at 300 °C and 30 MPa for 100 h than the Zn-containing alloy.