【摘要】 稀土掺杂钇铝石榴石（YAG）透明陶瓷是重要的固体激光器用增益介质材料。无容器凝固-非晶晶化法具有工艺简单,制备条件温和等优点,是极具潜力的YAG透明陶瓷制备新技术,但关于YAG熔体在无容器凝固中的相选择机制认识还不清楚。采用气动悬浮法对不同降温速率条件下钇铝石榴石（YAG）熔体无容器凝固过程中的相选择机制进行了研究。结果表明,在较低降温速率情况下,YAG熔体发生亚稳凝固,首先析出YAlO₃（YAP）相,并以树枝晶的方式生长,在枝晶间形成YAP/Al₂O₃共晶相。随着降温速率的增加,凝固组织中出现YAG相,形成稳态YAG相和亚稳态YAP/Al₂O₃相共存的组织;在53 K/s的降温速率下凝固时,熔体形成单相YAG的等轴晶组织。降温速率为250 K/s时不发生再辉,获得YAG非晶。非晶的玻璃化转变温度Tg和再结晶温度Tx分别为880和910℃。XRD结果表明非晶中包含有少量YAP和YAG的结晶相。更多还原

【Abstract】 Rare earth elements doped yttrium aluminum garnet（YAG） transparent ceramics are technologically important laser host materials. Containerless solidification-controlled crystallization（CSCC） solution is a promising new technology for preparation of YAG transparent ceramic because of its advantages of simple process and mild condition. However, the mechanism of phase selection of YAGmelt under containerless solidification condition is not clear. The containerless solidification of garnet Y₃Al₅O₁₂（YAG） was carried out using the aerodynamic levitation method at different cooling rates. The metastable YAlO₃ perovskite（YAP） and subsequent YAP+Al₂O₃ eutectic were formed when the melts of YAG solidified at the cooling rates of 4 K/s. The samples contained both the metastable YAP/Al₂O₃ and stable YAG phase were obtained by increasing the cooling rate to 13 K/s. When the cooling rates increased to about 53 K/s, the YAG melts formed into monophasic YAG. At the cooling rate of about 250 K/s, the glass-ceramics was successively obtained without recalescence. The glass transition temperature T_g and crystallization temperature T_x were 880 oC and 910 oC respectively. XRD results indicate that the glass-ceramics contains metastable YAP and YAG.更多还原