抄録
The Ws (Widmanstätten start) temperature vs. T0 (metastable equilibrium temperature of stress-free parent and product phases of the same composition) and the Bs (bainite start) temperature vs T0 comparisons so far made in ferrous and non-ferrous alloys are reviewed The Widmanstätten morphology begins to appear considerably above T0 in nearly all the ferrous alloys examined. The kinetic-Bs, defined approximately as the bay temperature in the TTT curve for the initiation of transformation, observed in some Fe–C–X alloys when X is a carbide former and in higher order alloys is well below or close to T0. However, the microstructural-Bs, defined as the maximum temperature at which a non-lamellar mixture of eutectoid decomposition products is formed, reported in Fe–C and Fe–C–Cr alloys does not appear to be related to T0. In titanium alloys, both Ws and microstructural-Bs are significantly higher than T0. In Ni–Cr, Cu–Zn and Ag-base alloys etc., it is possible that Widmanstätten and/or “bainite” plates are mostly formed above T0. In conjunction with the reported solute partitioning and other kinetic behaviors, the mechanism for the formation of plates is discussed.
