High-strength nanostructured Ti–12Mo alloy from ductile metastable beta state precursor

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 527; no. 16; pp. 4262 - 4269
• Main Authors: Sun, F., Prima, F., Gloriant, T.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.06.2010; Elsevier
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Elasticity. Plasticity; Exact sciences and technology; Fractures; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Metastable phases; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; Tensile test; Titanium alloy; Transmission electron microscopy; Titanium alloy; Transmission electron microscopy; Metastable phases; Tensile test; Levitation melting; Annealing; Ductility; Water quenching; High strength alloy; Rupture; X ray diffraction; Titanium base alloys; Tension test; Dilatometry; Molybdenum alloy; Precipitation; Nanoprecipitate; Transition metal alloy; Recrystallization; Elongation (mechanics)
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2010.03.044

In this study, the metastable beta Ti–12Mo (wt.%) alloy was synthesized by the cold crucible levitation melting (CCLM) method and then quenched in water from the beta domain. The tensile test carried out on the as-quenched alloy showed an important ductility reaching 45% of elongation before fracture. From the as-quenched metastable beta state, non-isothermal electrical resistivity and dilatometry measurements were carried out to detect the phase transition in order to control the nanophase precipitation sequence. After heating, XRD analysis and TEM observations revealed a very fine nano-scale omega and alpha precipitation in the beta matrix. Tensile test results indicated a very high strengthening effect after appropriate thermo-mechanical treatments, which was observed particularly huge after a two-step annealing process where a tensile strength as high as around 1600 MPa was obtained. This highly enhanced tensile strength was attributed to the complex intragranular nanostructure observed by TEM consisting of two-scale alpha nanoprecipitates inside sub-micrometer beta grains.