摘要
An ω phase with a primitive hexagonal crystal structure has been found to be a ωmmon metastable phase in body-centered cubic （bcc） metals and alloys. In general, ω phase precipitates out as a high density of nanoscale particles and can obviously strengthen the alloys; however, ωarsening of the ω particles significantly reduces the alloy ductility. The ω phase has ωherent interfacial structure with its bcc matrix phase, and its lattice parameters are aω ---- x/2 x abcc and ωbcc= v/3/2 abcc abet. The ωmmon { 112} （111）-type twinning in bcc metals and alloys can be treated as the product of the ω ~ bcc phase transition, also known as the ω-lattice mechanism. The ω phase＇s behavior in metastable 13-type Ti alloys will be briefly reviewed first since the ω phase was first found in the alloy system, and then the existence of the ω phase in carbon steels will be discussed. Carbon plays a crucial role in promoting the ω formation in steel, and the ω phase can form a solid solution with various carbon ωntents. Hence, the martensitic substructure can be treated as an ct-Fe matrix embedded with a high density of nanoscale ω-Fe particles enriched with carbon. The reωgnition of the ω phase in steel is expected to advance the understanding of the relationship between the microstructure and mechanical properties in bcc steels, as well as the behavior of martensitic transformations, twinning formation, and martensitic substructure.
Abstract An ω phase with a primitive hexagonal crystal structure has been found to be a ωmmon metastable phase in body-centered cubic （bcc） metals and alloys. In general, ω phase precipitates out as a high density of nanoscale particles and can obviously strengthen the alloys; however, ωarsening of the ω particles significantly reduces the alloy ductility. The ω phase has ωherent interfacial structure with its bcc matrix phase, and its lattice parameters are aω ---- x/2 x abcc and ωbcc= v/3/2 abcc abet. The ωmmon { 112} （111）-type twinning in bcc metals and alloys can be treated as the product of the ω ~ bcc phase transition, also known as the ω-lattice mechanism. The ω phase＇s behavior in metastable 13-type Ti alloys will be briefly reviewed first since the ω phase was first found in the alloy system, and then the existence of the ω phase in carbon steels will be discussed. Carbon plays a crucial role in promoting the ω formation in steel, and the ω phase can form a solid solution with various carbon ωntents. Hence, the martensitic substructure can be treated as an ct-Fe matrix embedded with a high density of nanoscale ω-Fe particles enriched with carbon. The reωgnition of the ω phase in steel is expected to advance the understanding of the relationship between the microstructure and mechanical properties in bcc steels, as well as the behavior of martensitic transformations, twinning formation, and martensitic substructure.
