过冷
热力学
非晶态金属
玻璃化转变
径向分布函数
焓
材料科学
分子动力学
无定形固体
金属间化合物
大气温度范围
热扩散率
Atom(片上系统)
化学
结晶学
冶金
合金
计算化学
聚合物
复合材料
嵌入式系统
物理
计算机科学
作者
Nicholas P. Bailey,Jakob Schiötz,Karsten W. Jacobsen
标识
DOI:10.1103/physrevb.69.144205
摘要
We have obtained effective medium theory interatomic potential parameters suitable for studying Cu-Mg metallic glasses. We present thermodynamic and structural results from simulations of such glasses over a range of compositions. We have produced low-temperature configurations by cooling from the melt at as slow a rate as practical, using constant temperature and pressure molecular dynamics. During the cooling process we have carried out thermodynamic analyses based on the temperature dependence of the enthalpy and its derivative, the specific heat, from which the glass transition temperature may be determined. We have also carried out structural analyses using the radial distribution function (RDF) and common neighbor analysis (CNA). Our analysis suggests that the splitting of the second peak, commonly associated with metallic glasses, in fact, has little to do with the glass transition itself, but is simply a consequence of the narrowing of peaks associated with structural features present in the liquid state. In fact, the splitting temperature for the Cu-Cu RDF is well above ${T}_{g}.$ The CNA also highlights a strong similarity between the structure of the intermetallic alloys and the amorphous alloys of similar composition. We have also investigated the diffusivity in the supercooled regime. Its temperature dependence indicates fragile-liquid behavior, typical of binary metallic glasses. On the other hand, the relatively low specific-heat jump of around ${1.5k}_{B}/\mathrm{atom}$ indicates apparent strong-liquid behavior, but this can be explained by the width of the transition due to the high cooling rates.
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