Observation and characterization of isothermal α″ in a new β-type titanium alloy.

Orthorhombic α″ phaseoften forms in Ti alloys through martensite transformation during quenching. Here, we report the formation of orthorhombic α″ phasein a low modulus β-Ti alloy during isothermal ageing. Thecoexists with α and ω phases, and remains stable for 120 h during ageing at 673 K. Thephase is highly coherent with the β matrix, sharing the same basic orientation relationship asphase://[0 0 2]α″, [1 0 0]β//[1 0 0]α″, [0 1 1]β//[0 1 0]α″. But differing from orthorhombicphase, the lattice constants ofphase are determined asa = 0.352 nm,b = 0.494 nm, andc = 0.464 nm. [ABSTRACT FROM AUTHOR]