New criterion in predicting glass forming ability of various glass-forming systems

Abstract

It has been confirmed that glass-forming ability (GFA) of supercooled liquids is related to not only liquid phase stability but also the crystallization resistance. In this paper, it is found that the liquid region interval (Tl – Tg) characterized by the normalized parameter of Tg/Tl could reflect the stability of glass-forming liquids at the equilibrium state, whilst the normalization of supercooled liquid region ΔTx=(Tx – Tg), i.e. ΔTx/Tx (wherein Tl is the liquidus temperature, Tg the glass transition temperature, and Tx the onset crystallization temperature) could indicate the crystallization resistance during glass formation. Thus, a new parameter, defined as ξ = Tg/Tl+ΔTx/Tx is established to predict the GFA of supercooled liquids. In comparison with other commonly used criteria, this parameter demonstrates a better statistical correlation with the GFA for various glass-forming systems including metallic glasses, oxide glasses and cryoprotectants.

Recent progress in metallic glasses in Taiwan

“…There have been a number of indices to evaluate the glass-forming ability of BMGs, such as g (¼ T g /T x þ T l ), T x /T l , DT x (¼T x À T g ), T rg (¼T g /T l ), T x /(T l À T g ), T g /T l þ T x /T g and (T x À T g )/(T l À T g ), where T g is the glass transition temperature, T x the crystallization temperature, and T l the liquidus temperature. In 2007, it was further developed some more reliable parameters, one [25,26], and the other is k ¼ DT x /T x þ T g /T l [27].…”

Evaluation of glass-forming ability criterion from phase-transformation kinetics

“…Most of them comply with Rule 1 except T rg . γ do not comply with Rules 2 and 3, however, ω [11], ω 2 [12] and ξ [13] comply with Rule 2 and partially with Rule 3. Thus, from this work's point of view, we can predict that, among the criteria listed in Table 3, ω, ω 2 and ξ are the most proper criteria, γ takes the second place, T rg is the most inferior.…”

Evaluation of glass-forming ability for bulk metallic glasses based on characteristic temperatures

“…Hence, a number of parameters which can easily be determined from differential thermal analysis (DTA) or differential scanning calorimetry (DSC) have been proposed to reflect the GFA of alloys. Their representatives include T rg (=T g /T l ) [6,7], DT x (=T x À T g ) [8], c(=T x /(T g +T l )) [9,10], DT rg (=(T x À T g )/(T l À T g )) [11], a(=T x /T l ) [12], b(=T x /T g +T g /T l ) [12], d(=T x /(T l À T g )) [13], u(=T rg (DT x /T g ) 0.143 ) [14], c m (=(2T x À T g )/T l ) [15], b(=T x  T g / (T l À T x ) 2 , hereafter referred to as b 2 ) [16] and n(=DT x /T x +T g /T l ) [17]. Here, T g , T x and T l are the glass transition, onset crystallization and liquidus temperatures, respectively.…”