Interface Motion in Phase Transformations. Transformations in Iron and Iron-9 Percent Nickel Alloys

摘要

Thermal arrest, hot stage microscopy and transmission electron microscopy techniques have been employed to study the transformations in low carbon iron and iron-9% nickel alloys. In continuous cooling experiments, both series of alloys transform at an essentially constant temperature for cooling rates below the critical rate required for martensite formation. However, the high temperature transformation in pure iron takes place by a different mechanism than that in the 9% nickel alloys. Pure iron exhibits an equiaxed alpha structure with a low and random dislocation density while the 9% nickel alloy exhibits a cell like substructure analogous to that of low carbon martensite. This same cell like substructure characterizes upper bainite in higher carbon materials. (Author)