Zirconium (Zr)-based alloys, a new class of hard-tissue replacement materials, show lower strength compared to traditional medical metal materials such as stainless steel, cobalt alloy, and Ti-6Al-4V alloys, which may lead to premature fracture of the implant. Spinodal decomposition can increase the strength greatly without an increase in the elastic modulus of the alloy. In this study, a phase field method based on the Cahn–Hilliard equation was applied to the simulation of the spinodal decomposition in Zr–Nb alloys. The spinodal region on the Zr–Nb phase diagram was calculated by the phase field method by considering the interfacial energy and elastic strain energy contribution to the total Gibbs free energy. Furthermore, the effects of the Nb content and heat-treatment temperature on the morphology, amplitude, and volume fraction of the decomposition phases are discussed. Simulation results indicate that the morphology of the β′ phase is interconnected and regular with a preferential alignment in the ⟨110⟩ direction to reduce the strain energy, which may restrict the spinodal decomposition of the alloys. The two droplet phases merge, which can be attributed to the reduction in the elastic strain energy. The phase decomposition rate increases with an increase in aging temperature, but the aging temperature has only a small influence on the final volume fraction of the β′ phase.

Ti–22Nb–xZr and Ti–22Nb–xMo (x = 0, 2, 4, 6, in atom percent) were prepared by an arc melting method. The alloys were solution‐treated at 1073 K for 1.8 ks followed by quenching them into ice water, and the electrochemical corrosion behavior in a 0.9% NaCl solution at 25 °C and neutral pH range of the solution‐treated alloys was evaluated by using electrochemical impedance spectroscopy, polarization curves and an equivalent circuit analysis. It was found that the microstructure of the solution‐treated Ti–22Nb alloy mainly contains β phase with small amount of α″ phase, and the addition of Zr or Mo to a Ti–22Nb alloy is efficient to stabilize the β phase. The resulting impedance parameters and passive current densities indicated that the corrosion resistance of the Ti–22Nb alloy was promoted significantly with the addition of Zr and Mo.

In this study, an in situ β–Ti–Nb composites reinforced with TiC particles with an ultrafine grain size were fabricated using a powder metallurgical (PM) method. The microstructures and mechanical properties of the composites were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and compression tests. TiC particles were formed in the ball-milled powders after annealing at 600 °C due to a chemical reaction between stearic acid and titanium. Using high-pressure sintering (HPS) on an apparatus with six tungsten carbide anvils, a fully dense β–Ti–Nb composite reinforced with fine in situ TiC particles was obtained. The TiC particles exhibit particle sizes of ~500 nm, uniformly distributed in the composite matrix, which had grain sizes of ~600 nm. Thus, the TiC–β–Ti–Nb composite show very high compression yield strength and relatively high plasticity contributed by grain refinement and TiC particles strengthening. The composite with 45 vol.% TiC exhibited excellent mechanical properties, with a yield compressive strength of 1990 MPa and plastic strain of 9.12%. More over, a modified rule-of-mixture (ROM) was presented to describe the combined strengthening effect of grain refinement and TiC particles.

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A thin strip of a Zr -based alloy with a composition of Zr 60 Cu 25 Fe 5 Al 10 (in atom percent) was used as a raw material, and the composite coatings containing Zr -based amorphous phase and crystallites on Ti substrate were fabricated by a one-step laser cladding method without protection. The microstructure, phase constitution, microhardness and wear properties of the coatings were investigated. The results indicate that the microstructure of the coatings is strongly dependent on the laser scanning speed under the conditions of the laser power of 1300 W and laser beam diameter of 6 mm, and the composite coating mainly containing amorphous phase with a small amount of the crystallites can be obtained at the laser scanning speed of 10 mm/s. The composite coating exhibits much higher microhardness than the pure Ti substrate, and thus it behaves superior wear resistance in comparison with the substrate.