CAJ | 학술논문

应用双模PFC模型,计算二维PFC相图,模拟二维六角晶格向正方晶格的结构转变过程,观察新相(二维正方相)的形核、长大特点,以及相结构转变的动力学特征.结果表明:六角结构相向正方结构相的转变,正方相最易在六角相晶界处,尤其是在三晶粒的交汇处首先生成正方相的晶核,之后是正方相逐渐通过吞噬六角相的边缘,向六角相内部推进,并不断长大.对于结构转变生成的正方相晶粒,其晶粒取向几乎是随机的,与原先六角相晶粒取向角没有明显的关系.正方相转变的面积分数随时间变化的动力学曲线呈现典型的“S”形.由Avrami曲线可将相变曲线看成由两阶段组成.计算模拟得到的Avrami曲线的第二阶段直线斜率K的范围在2.0和3.0之间,与JMAK理论的指数n相符合.
응용쌍모PFC모형,계산이유PFC상도,모의이유륙각정격향정방정격적결구전변과정,관찰신상(이유정방상)적형핵、장대특점,이급상결구전변적동역학특정.결과표명:륙각결구상향정방결구상적전변,정방상최역재륙각상정계처,우기시재삼정립적교회처수선생성정방상적정핵,지후시정방상축점통과탄서륙각상적변연,향륙각상내부추진,병불단장대.대우결구전변생성적정방상정립,기정립취향궤호시수궤적,여원선륙각상정립취향각몰유명현적관계.정방상전변적면적분수수시간변화적동역학곡선정현전형적“S”형.유Avrami곡선가장상변곡선간성유량계단조성.계산모의득도적Avrami곡선적제이계단직선사솔K적범위재2.0화3.0지간,여JMAK이론적지수n상부합.
The two-mode phase-field-crystal (PFC) method is used to calculate the phase diagram and to simulate the transformation of hexagonal to square structure in two dimensions. The nucleation, grain growth and dynamic feature of the phase structure transforma-tion show that square phase prefers to be present at the juncture place of the three hexagonal grains, and swallows the hexagonal phase at grain boundary. The square grains grow and push the boundary of hexagonal grain toward the inside of hexagonal grain and then the square grains grow up and extend the area of square phase. The orientations of new square grains due to the structure transformation are nearly randomly distributed, and have no relation to those of hexagonal grains. The dynamic curve of area fraction of square phase shows the typical“S”shape with time increasing. The Avrami index curve shows that there are two stages in the transformation. The Avrami index n of second satge in simulation is in a range from 2.0 to 3.0, which is in good agreement with the value from the JMAK theory.