熔体的粘度,亚稳相,相变和相图 Ⅱ.熔体中的不连续结构相变

Viscosity,metastable phase,phase transition and phase diagram of melts Ⅱ.A discontinuous structure change in melts

实验和理论表明,粘度是一个能明确表征和反映熔体中存在的亚稳相和这些相之间转变特征的“好”物理量.表征熔体中亚稳相特征具有宏观参量(η0,ε)又有微观参量(df);是一类有别于其它有液-液相变液体的(例如4He,液晶)新的液相.熔体中亚稳相之间的转变是一类新的LLPT:第1,是可逆的一级相变:在相变点两相平衡并服从相律;第2,是不连续结构转变并有两种突变形式:热缩(吸收蒸发热),热胀(放出凝结热).对任意组分的熔体均有相似的亚稳相特征和相变特征.

The viscosity η of liquid metal and its alloys is proved experimentally and theoretically to be a “good” physical parameter to characterize definitely the existence of metastable phases and the transition behaviors between them. The metastable phase in mchs is distinguished by both macro-phase parameters （ η0, ε ） and micro-phase parameter （ df）. A new liquid phase is formed and the transition between these metastable phases is a new kind of Liquid-Liquid Phase Transition with the following characteristics. Firstly, the two phases are in an equilibrium state at the phase transition point, the phase transition obeys equilibrium thermodynamics phase rule and belongs to a reversible first-order phase transition. Secondly, it is a discontinuous structure change with two possible forms of thermal contraction （thennal absorption） or thermal expansion（thermal release）. The melts with any composition possess similar features such as metastable phase and phase transition.