摘要
利用双光束激光干涉热膨胀仪研究了La55Al25Ni10Cu10金属玻璃在玻璃转变温度以下亚稳状态下的热膨胀变化行为。对La55Al25Ni10Cu10金属玻璃在300～423 K进行了两次加热并测量其长度变化和热膨胀系数。在第一次加热过程中,样品的热膨胀系数随温度升高缓慢降低,在接近玻璃转变温度时,热膨胀系数降低幅度减小,这些现象是升温过程中的结构弛豫造成的。第二次加热过程的热膨胀系数低于第一次加热过程并且仍然是随温度升高而降低,说明样品的结构弛豫仍然在进行,并且两次加热过程中的结构弛豫是不可逆的。两次加热过程中的热膨胀系数变化是自由体积在结构弛豫过程中的减少导致的结构变化造成的。
The thermal expansion of La55Al25Ni10Cu10 bulk metallic glass below glass transition temperature in the metastable state was studied using a du- al - beam laser interferometric dilatometer. The thermal expansion of the sample was measured twice in the repeat heating process from 300K to 423K. The thermal expansion coefficient of the sample decreased slowly with the temperature increasing in the first heating process because of the structural relaxa- tion. The decreasing amount of the thermal expansion coefficient became smaller with the temperature approaching the glass transition temperature because the sample was close to the equilibrium state. The thermal expansion coefficient kept decreasing in the second heating process but the value was smaller than the first heating process reflecting that the structural relaxation was still in progress and it was an irreversible process. The structural changes caused by the free volume decreasing in the structural relaxation process lead to the decreasing of the thermal expansion coefficient in the heating process.
出处
《轻金属》
CSCD
北大核心
2013年第7期57-60,共4页
Light Metals
基金
高等学校博士学科点专项科研基金(20100006110013)
中央高校基本科研业务费专项资金(FRF-TP-09-026B)
关键词
大块金属玻璃
热膨胀
结构弛豫
bulk metallic glass
thermal expansion
structural relaxation
