合金元素及热处理条件对LaNiAlM合金结构及储氚固氦行为的影响

By means of combining computational and experimental techniques, the effect of alloying elements and heat treatment regime upon phase composition, crystal structure and lattice stress of LaNiAlM alloys prepared by adding appropriate amount of alloying element M into LaNiAl master alloy will be systematically investigated. And the atomic site occupation and distribution of the alloying elements in the unit cell will be determined. Meanwhile, the corresponding relationship between composition & structure and thermodynamic parameters, hydrogen storage capacity, plateau pressure, plateau slope, plateau hysteresis, activation behavior, kinetic performance, pulverization resistance, disproportionation resistance，cycle life and helium retention behavior, respectively, will be explored. In addition, the thermodynamic isotope effect at varying temperature will be summarized in order to predict the equilibrium pressure of the tritide by measuring that of the hydride. Moreover, a simulation method for the quick evaluation of helium retention capability, which is practically consistent with tritium aging results, will be established and the alloy selection period will be noticeably shortened. In a word, this project aims at providing theoretical reference for the development of new type tritium storage materials with low equilibrium pressure at room temperature and mild tritium absorption/desorption conditions.

以La-Ni-Al体系为基本成分，添加适量的合金元素M制备LaNiAlM合金，通过计算模拟与实验相结合的手段，系统研究合金元素及热处理条件对合金的相组成、晶体结构及晶格应力的影响，确定各元素原子在晶胞中占位及分布状态。探索合金成分及结构与其热力学参数、储氢量、平台压、平台斜率及滞后效应、活化及动力学性能、抗粉化、抗岐化性能、循环寿命及固氦行为的对应关系。总结出该体系在不同温度下的热力学同位素效应规律，达到从氢化物平衡压推测氚化物平衡压的目的。建立与长期氚时效实验结果基本相符的固氦性能快速模拟评价手段，显著缩短合金的遴选周期，为发展室温平衡压低、吸放氚条件温和的新型储氚材料提供理论参考。

氚是一种应用广泛的战略资源，氚的安全储存问题一直受到高度重视。作为放射性氢同位素的氚，通常以金属氚化物的形式储存，为保证操作便捷及安全，要求储氚（氢）材料具有良好的吸放氚性能和较强的“固氦”能力，即经过较长的储氚期后，绝大部分氚衰变产生的氦能保留在材料中，不致由于氦的大量释放而使储氚容器内压陡然升高而发生事故。因此，深入、系统地研究诸多影响材料结构及其储氚固氦特性的因素及其作用规律，对发展新型高效储氚材料至关重要。本课题系统研究了Mn、Al替代以及制备工艺和热处理温度对LaNiAl系储氢合金的晶体结构、活化、吸放氢平台压力、热力学和动力学性能的影响。进行了LaNi3.8Al1.0Mn0.2合金及其氘化物LaNi3.8Al1.0Mn0.2D3.2的中子粉末衍射研究，确定了合金的微观结构及各元素原子的空间占位。通过热解析和弹性反冲分析研究了LaNi3.8Al1.0Mn0.2合金薄膜中氦的行为。通过第一原理计算研究了La-Ni-H、La-Ni-Al-H和La-Ni-Al-Mn-H氢化合物的晶体结构、电子结构和热力学稳定性。通过理论计算和实验，研究了LaNi5-xAlx (x=0, 0.25, 0.5, 0.75)合金的热力学氢同位素效应。上述工作为研发及遴选室温平衡压低、吸放氚条件温和的新型储氚材料提供了理论和实验参考。