The mechanism of hydrogen-accelerated melting of polycrystalline copper.
The mechanism of hydrogen-accelerated melting of polycrystalline copper.
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多晶铜氢加速熔化机理
DOI：
10.1039/d0cp05828a
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Y. Lü
中科院分区：
文献类型：
--
作者：
Haishen Huang;L. Ai;Min Chen;Y. Lü
利用新开发的Cu/H ReaxF力场研究了掺氢多晶铜的熔化过程。研究发现，氢原子能有效地促进铜的熔化，甚至在快速加热时低于铜的平衡熔化温度时才能发生。强化熔化与氢原子与晶界的相互作用密切相关。我们发现，宿主铜原子作为预熔的先驱，在晶界附近表现出协同振动。氢原子的掺杂使振动更加剧烈，晶界变宽，预熔被提前触发。同时，随着温度的升高，晶界偏聚的氢原子大量扩散到块体区域，导致体相的晶格扭曲加剧。这有利于熔化过程中液-固界面的快速推进，而不同于无氢多晶铜的缓慢和不连续的界面推进。我们的结果表明，即使是少量的氢原子也有望在存在结构缺陷的情况下显著影响金属的热力学性质。
We investigate the melting process of polycrystalline copper doped with hydrogen atoms by using the newly developed Cu/H ReaxFF force field. Hydrogen atoms are found to effectively promote the melting of copper, and even make it happen at temperatures below the equilibrium melting temperature of copper during rapid heating. The enhanced melting is closely relevant to the interaction of hydrogen atoms with the grain boundary. We find that host Cu atoms perform cooperative vibration around the grain boundaries as the precursor of premelting. The doping of hydrogen atoms is shown to drive the vibration more violent so that the grain boundary becomes broader and the premelting is prematurely triggered. Meanwhile, hydrogen atoms segregated in grain boundaries massively diffuse into the bulk region with increasing temperature, resulting in intensification of lattice distortion of the bulk phase. This facilitates the rapid advancement of the liquid-solid interface during melting in contrast to the slow and discontinuous interface advancement in hydrogen-free polycrystalline copper. Our results suggest that even a small amount of hydrogen atoms is expected to significantly affect the thermodynamic properties of metals with the existence of structural defects.