Unification of characteristic temperature-based glass-forming ability and stability criteria

•A new GFA & GS tetrahedron is constructed from pseudo-four characteristic parameters.•A modified GFA & GS criterion is derived: G-FASm=Tx/Tl+((Tx-Tg)/(Tl-Tg))0.3.•Unification of criteria from vertices, edges, faces and the entire body of the T-FAS.•Criteria expressions are unified by two complex temperatures parameters Trg and Txg. The various criteria of glass-forming ability and stability (GFA & GS) based on the three characteristic temperatures (glass transition temperature Tg, the onset crystallization temperature Tx and the liquid temperature Tl) are uneven and inconsistent, and even contradictory. It is urgent to find a new method that comprehensively considers the GFA from cooling process and the GS from heating process, and unifies the GFA & GS criteria. In this paper, based on Tg, the tetrahedron for evaluating GFA & GS (T-FAS) with pseudo-four characteristic parameters as vertexes is constructed from four aspects (1. The onset crystallization temperature Tx: resistance to crystallization; 2. The liquid temperature Tl: high temperature liquid stability; 3. The supercooled liquid region of glass (SLRglass) ΔTx = Tx-Tg (or the ratio of Tx to Tg, i.e., crystallization-vitrification ratio Tx/Tg): stability of SLRglass; 4. The supercooled liquid region of melt (SLRmelt) ΔTg = Tl-Tg (or the reduced glass transition temperature Trg): glass-forming ability/tendency of glass itself) involved two processes of GFA in cooling process and GS in heating process, from which the G-FAS criterion is derived and modified, and its wide applicability is compared and evaluated with other criteria. Finally, the existing characteristic temperature-based GFA & GS criteria are unified from the vertices, edges, faces and the entire body of the T-FAS, and the expressions are also unified by GFA & GS reflected by Tg (i.e., two complex characteristic temperatures parameters Tg/Tl and Tx/Tg). [Display omitted]