Liquid-Liquid Transitions due to Melting Temperatures of Residual Glassy Phases Expected in Pt57Cu23P20

Abstract

Bulk glasses are obtained by quenching melts of various compositions. The initial temperature is chosen above the liquidus temperature (T 1 ) of materials assuming that the melt is homogenous. Glassy items are formatted above the glass transition temperature T g below a crystallization temperature called T x . First-order transitions at T x transform melts into composites containing crystals and new glassy phases, melting at temperatures (T n+ ) much higher than (T 1 ). These first-order transitions were studied at Caltech Pasadena by cooling and heating a melt of Pt 57 Cu 23 P 20 . A recent model predicting the formation enthalpies of these new composites at T x and the melting temperatures (T n+ ) of glassy fractions is applied to this alloy.

NiTi2, a New Liquid Glass

“…The exothermic enthalpy is either totally attributed to crystallization with CHN without considering any homogeneous nucleation because the liquid is viewed as being homogenous above T m , or only partially to the nucleation of a glassy fraction depending on the nucleation temperature of first-order transition with NCHN [29,32,37]. Recent examples of these two approaches are devoted to the undercooling of Pt 57 Cu 23 P 20 alloy [31,38].…”

“…This equation is used after application of very high temperatures, and the undercooling reduced temperature is directly equal to θ x and ∆ε lg = −∆ε (see for example [31]).…”

“…Undercooling with or without crystallization is observed during the first cooling depending on the cooling rate. The enthalpy coefficient ∆ε lg , equal to singular values of Phase 3, results from this first-order transition [31]. Heating from the glass state can produce a first-order transition between T m and T g with or without crystallization.…”

Multiple Glass Transitions in Bismuth and Tin beyond Melting Temperatures

“…These transitions often result from the separation of two liquid states, occurring in all supercooled materials at a temperature T x < T m , including pure elements in which two liquid phases of the same composition coexist. A liquid fraction crystallizes at T x and melts at T m while the complementary glassy fraction melts at T n+ = T g [22][23][24]. The purpose of this publication is to relate all the Liquid-liquid transitions, occurring above the melting temperature (T m ) in Bi and Sn up to (2 T m ), and beyond, to glass transition temperatures [1,3,4].…”

“…The values of T n+ were determined from singular values of G-phase frozen enthalpy, employing the nonclassical homogeneous nucleation (NCHN) model to predict T x , T n+ and the enthalpy. Singular values of (f ) leading to (T n+ ) correspond to percolation thresholds of broken bonds (configurons) leading to glassy phases during cooling below T n+ [24,29,30,33,34].…”