Precipitation hardening and microstructure evolution of the Ti–7Nb–10Mo alloy during aging

• The ωathin quenched alloy transformed to ωisoor α at different temperatures.
• ST alloy with ωath + β microstructure showed 80 GPa modulus and 20% elongation.
• The alloy was highly embrittled by the ωisoand α phases formed during aging.
• The ST alloy showed better corrosion resistance than Ti-6Al-4 V alloy.

A biomedical β titanium alloy (Ti–7Nb–10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ωath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β + ωath → β + ωiso (144 h) at Taging = 350–400 °C, β + ωath → β + ωiso + α → β + α at Taging = 500 °C, and β + ωath → β + α at Taging = 600–650 °C, where ωiso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4 V alloy, the Ti–7Nb–10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti–7Nb–10Mo alloy is promising for biomedical applications.

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