金属硅化物熔体中不同形貌SiC晶体的生长

Growth of different morphological SiC crystals from metal silicide fluxes

以过渡族金属硅化物为溶剂,采用自发熔渗法和溶液法来研究不同形貌SiC晶体在金属硅化物熔体中的生长情况.利用光学显微镜(OM)、扫描电镜(SEM)、体视显微镜等对熔渗试样和采用溶液法生长的单晶和晶须的形貌结构进行了观察和表征,利用X射线衍射仪(XRD)对采用溶液法生长的晶体和晶须进行了相组成和晶型的表征,并讨论了SiC晶须和SiC单晶的生长机理.结果表明,Fe5Si3、CoSi、Co4.5CrSi4.5、Ti2.3Si7.7等熔体适合生长SiC单晶,FeSi、FeSi2等熔体适合生长SiC晶须,而当Fe3Si熔体渗入SiC预制件后,仅有石墨相析出.

Experiments of growth of SiC crystals from transition metal silicide fluxes were performed by two methods： melt infiltration of transition metal silicide fluxes into SiC powder preforms and solution growth of SiC from the fluxes. The microstructures of the samples were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and stereoscopic microscope, and the crystal phases and the whisker grown from the metal silicide fluxes were analyzed by X-ray diffraction （XRD）. The growth mechanisms of SiC whisker and SiC single crystal were discussed. Results show that Fe5Si3, CoSi, Co4.5CrSi4.5 and Ti2. 3Si7.7 alloys are suitable for the growth of SiC single crystal, and FeSi, FeSi2 alloys prone to the synthesis of SiC whiskers. The dissolution of SiC in Fe3 Si melts leads to carbon precipitation.