非晶态(Ni_(80)P_(20))合金的玻璃转变和过冷液体性质

Revealing Glass Transition and Supercooled Liquid in (Ni_(80)P_(20)) Metallic Glass

镍磷(Ni_(80)P_(20))金属玻璃是最典型和被研究最多的金属玻璃成分之一。然而,由于镍磷金属玻璃在加热过程中玻璃转变过程被晶化所阻断,到目前为止其过冷液体性质还没有被探测和表征。本工作通过具有高升温速率的超快量热仪,避免了(Ni_(80)P_(20))金属玻璃在玻璃转变过程中的晶化,直接探测其整个玻璃转变过程和一定温度宽度的过冷液相区,为揭示其超冷液体性质提供了可能。通过超快量热测量,获得了(Ni_(80)P_(20))金属玻璃在5个数量级升温速率变化下的相形成规律和液体脆度,它的超冷液体展现出比大部分块体金属玻璃更"脆"的一种液体行为,这种"脆"性液体行为可能导致其差的玻璃形成能力。

Nickel-phosphorus metallic glass(MG) is one of the most typical MGs, and is also one of the most popular studied MG components, especially in the process of establishing the structure model of amorphous alloys and computer simulations. Although it appears throughout the history of amorphous alloy research, its glass transition temperature and liquid properties have not yet been determined due to its low ability to form glass. In this work, we bypassed the crystallization of (Ni_(80)P_(20)) MG during the glass transition process by an ultrafast calorimeter with heating rates up to thousands of Kelvin per second and directly detected its glass transition process. This method offers an opportunity to expose the nature of the (Ni_(80)P_(20)) MG supercooled liquid. The liquid fragility of the metallic glass Ni80P20 was determined by the Vogel-Fulcher-Tammann equation based on the dependence of the glass transition temperature at different heating rates. The results show that the liquid fragility of (Ni_(80)P_(20)) MG is 93 ± 4, which is obviously a very"fragile"liquid compared with other bulk MGs. It is suggested that this"fragile"liquid behavior of (Ni_(80)P_(20)) MG may lead to its low glass-forming ability.