On the parameters to assess the glass forming ability of liquids

Glass Forming Ability and Mechanical Properties of Quinary Zr-Based Bulk Metallic Glasses

“…All the derived quinary compositions have high values in different GFA criteria proposed by many investigators such as T rg , ÁT x , and 4-6) ( ¼ T x =ðT g þ T l ) and ¼ T x =T l ) compared to the quaternary alloy. Among the alloys, the Zr 58 Cu 22 Co 4 Fe 4 Al 12 alloy has a very wide supercooled temperature region of about 115 K and highest and values, which have been proven to be better GFA criteria than the reduced glass transition temperature (T rg ), 5,6) suggesting that this alloy can be cast into a larger diameter than the quaternary alloy.…”

Influence of Casting Parameters on the Critical Casting Size of Bulk Metallic Glass

“…[1][2][3][4][5][6][7][8][9][10] For example, Zr-, Pd-, Ln-, and Mg-based BMGs have R C values below~100°C/s and, hence, are considered as having high GFA. [1][2][3][4][5][6][7][8] Over the past 40 years, numerous parameters have been proposed for predicting the ease of glass formation and glass stability in these materials, with examples including the following: the reduced glass-transition temperature or Turnbull's principle T rg = T g /T l ; [11,12] the supercooled liquid interval DT X = T X À T g ; [6] c = T X /(T g + T l ); [13] c m = (2T X À T g )/T l ; [14] DT rg = (T X À T g )/(T l À T g ); [15] d = T X /(T l À T g ); [16] u = T rg (DT X /T g ) 0.143 ; [17] a = T X /T l ; [18] b = T X /T g + T g /T l ; [18] b I = T X 9 T g /(T l À T X ) 2 ; [19] and more recently x = T g /T X À 2T g /(T g + T l ), [20] where T X and T l are the onset crystallization temperature and liquidus temperature, respectively. In general, there is no single parameter that accurately correlates GFA to a specific parameter in all alloy systems, with trends often corresponding well in some systems but not as well in others.…”

“…[20,21] With reference to the aforementioned glassforming parameters, it can be seen that they explicitly relate T g , T X , and T l (determined by heating rather than cooling) with the GFA, R C , and critical casting thickness Z C . [6,[11][12][13][14][15][16][17][18][19][20] Further, the former are known to vary marginally with the heating rate, depending on the fragility of the individual glass, whereby a faster heating rate yields higher values of T g and T X [22,23] and increases the size of DT X . [22] Hence, from a physical metallurgy perspective, the only quantitative measure of GFA is the critical cooling rate, despite the difficulties in determining this parameter.…”

Computer simulations of glasses: the potential energy landscape

“…To date, glass-forming ability has been described somewhat phenomenologically, for example, in the form of time-temperature-transformation curves (TTT) [246,247]; other empirical formulae use the liquidus, crystallisation and glass transition temperatures to derive a parameter capable of predicting whether a bulk metallic glass has a high glass forming ability [13][14][15]. Experimentally, it has been possible to map the glass-forming ability of a 5-component alloy in composition space.…”