CAJ | 학술논문

采用分子动力学方法对液态Ca70Mg30合金快速凝固过程中纳米团簇结构的形成和演变特性进行模拟。采用原子团类型指数法(CTIM)对凝固过程中纳米团簇结构的演变进行分析。结果表明：系统在5×1011 K/s的冷速条件下形成以1551、1541和1431为主的非晶态结构，非晶转变温度约为530 K；(120120)二十面体基本原子团对系统非晶结构的形成起到决定性的作用，并且原子半径较小的Mg原子更容易占据二十面体基本原子团中心原子的位置；同时，纳米团簇主要是通过中等尺寸团簇的合并而形成，纳米级大团簇的形成演变过程呈现出类似于非晶晶化过程的3个阶段式的变化。
채용분자동역학방법대액태Ca70Mg30합금쾌속응고과정중납미단족결구적형성화연변특성진행모의。채용원자단류형지수법(CTIM)대응고과정중납미단족결구적연변진행분석。결과표명：계통재5×1011 K/s적랭속조건하형성이1551、1541화1431위주적비정태결구，비정전변온도약위530 K；(120120)이십면체기본원자단대계통비정결구적형성기도결정성적작용，병차원자반경교소적Mg원자경용역점거이십면체기본원자단중심원자적위치；동시，납미단족주요시통과중등척촌단족적합병이형성，납미급대단족적형성연변과정정현출유사우비정정화과정적3개계단식적변화。
A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid Ca70Mg30 alloy. The cluster-type index method (CTIM) was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5×1011 K/s, and glass transition temperature Tg is about 530 K;the icosahedron cluster of (12 0 12 0) plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.