•Nb-25Ti-xTa (x = 10, 15, 20, 25, 35 at.%) alloys were fabricated by powder metallurgy.•The content of Ta and the sintering temperature would adjust the phase composition.•Nb-Ti-Ta alloys have the potential to induce apatite in vitro and a high biocompatibility.•Nb-Ti-Ta alloys are quite promising as a new candidate of biomedical application.Microstructures, mechanical properties, apatite-forming ability and in vitro experiments were studied for Nb-25Ti-xTa (x = 10, 15, 20, 25, 35 at.%) alloys fabricated by powder metallurgy. It is confirmed that the alloys could achieve a relative density over 80%. Meanwhile, the increase in Ta content enhances the tensile strength, elastic modulus and hardness of the as-sintered alloys. When increasing the sintering temperatures, the microstructure became more homogeneous for β phase, resulting in a decrease in the modulus and strength. Moreover, the alloys showed a good biocompatibility due to the absence of cytotoxic elements, and were suitable for apatite formation and cell adhesion. In conclusion, Nb-25Ti-xTa alloys are potentially useful in biomedical applications with their mechanical and biological properties being evaluated in this work.

Porous and dense TiNi alloys were successfully fabricated by powder metallurgy (P/M) method, and to further improve their surface biocompatibility, surface modification techniques including grind using silicon-carbide (SiC) paper, acid etching and alkali treatment were employed to produce either irregularly rough surface or micro-porous surface roughness. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) attached to SEM were used to characterize surface structure and the Ca-P coatings. Effects of the above surface treatments on the surface morphology, apatite forming ability were systematically investigated. Results indicate that all the above surface treatments increase the apatite forming ability of TiNi alloys in varying degrees when soaked in simulated body fluid (SBF). More apatite coatings formed on TiNi samples sintered at 1050° and 1100° due to their high porosity and pure TiNi phase that is beneficial to heterogeneous nucleation. Furthermore, more uniform apatite was fabricated on the sample sintered from the mixture of Ni and Ti powders.

This study presented nanosized WC-Co composite powders synthesized using a one-step reduction-carbonization process with a combination of CH4/H2 as a gas carbon source and soluble starch as an in situ carbon source. The results of carbon analysis and X-ray diffraction revealed that WC-Co nanocomposite powders with a pure WC and Co phase could be obtained at 1100 °C after 0.5 h. A higher gas flow ratio of CH4/H2 during the reduction-carbonization process led to a higher total carbon content of the sample. A field emission scanning electron microscope confirmed that the particles in the WC-6 wt% Co composite powders had the lowest average size of 43 nm with equiaxed shapes. A sintering neck was observed in the WC-3 wt% Co composite powders whereas faceted particles were found in the WC-12 wt% Co composite powders. Moreover, this method has advantages of simple processing, rapid synthesis and good applicability in potential industry application.

FeCrAl(f)/HA biological functionally gradient materials (FGMs) were successfully fabricated by the hot pressing technique. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and bending strength test machine were utilized to characterize the microstructure, component, mechanical properties and the formation of the Ca-deficient apatite on the surface of these materials. The results indicate that an asymmetrical FeCrAl(f)/HA FGM, consolidating powders prepared by mixing HA with 3%–15% (volume fraction) is successfully prepared. Both of the matrix and FeCrAl fiber are integrated very tightly and bite into each other very deeply. And counter diffusion takes place to some extent in two phase interfaces. The elemental compositions of the FeCrAl(f)/HA FGM change progressively. Ca and P contents increase gradually with immersion time increasing, and thereafter approach equilibrium. The bone-like apatite layer forms on the materials surface, which possesses benign bioactivity, and the favorable biocompatibility can provide potential firm fixation between FeCrAl(f)/HA asymmetrical FGM implants and human bone.

•A novel approach for the fabrication of porous TiNi scaffolds•Macroporous structures are replicated from the polymer sponge template.•The pore characteristics and mechanical properties of TiNi scaffolds agree well with the requirement of trabecular bone.•Cytocompatibility of TiNi scaffolds is assessed, and it closely associated with pore property.The superelastic nature of repeating the human bones is crucial to the ideal artificial biomedical implants to ensure smooth load transfer and foster the ingrowth of new bone tissues. Three dimensional interconnected porous TiNi scaffolds, which have the tailorable porous structures with micro-hole, were fabricated by slurry immersing with polymer sponge and sintering method. The crystallinity and phase composition of scaffolds were studied by X-ray diffraction. The pore morphology, size and distribution in the scaffolds were characterized by scanning electron microscopy. The porosity ranged from 65 to 72%, pore size was 250–500 μm. Compressive strength and elastic modulus of the scaffolds were ~ 73 MPa and ~ 3GPa respectively. The above pore structural and mechanical properties are similar to those of cancellous bone. In the initial cell culture test, osteoblasts adhered well to the scaffold surface during a short time, and then grew smoothly into the interconnected pore channels. These results indicate that the porous TiNi scaffolds fabricated by this method could be bone substitute materials.

Porous TiNi binary and TiNiNb ternary alloys of four compositions (Ti50Ni47.5Nb2.5, Ti50Ni45Nb5, Ti50Ni42.5Nb7.5, and Ti50Ni40Nb10) were fabricated by the elemental powder sintering process. The effects of Nb addition on microstructure and mechanical properties of TiNi(Nb) alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and tensile tests, respectively. With the increase of Nb contents, the TiNi matrix as the main phase is always retained, while the intensity of its diffraction peak gradually became weak with the appearance of β-Nb and TiNb phases. Most Nb particles are well-distributed in the TiNi matrix and (Ti,Nb)2Ni phase is found in the binding domain between Nb phase and TiNi phase. The tensile strength and elastic modulus of TiNiNb alloys increase with the increase of Nb contents, due to the solid solution strengthening effect of Nb-rich particles, the enlarged sintering neck and the strengthened bond between particles. Consequently, Nb plays a crucial role in adjusting composition and improving microstructure and mechanical properties of TiNiNb alloys.

•WC-10Co composite powders were synthesized by the method with carbon boat added.•The carbon boat could adjust the carbon activity spontaneously during the reduction-carbonization process.•The carbon boat affected the microstructure and particle size of the composite powders.WC-10Co composite powders without carbon deficient phase and free carbon could be synthesized by the method with carbon boat added in the reduction-carbonization process. The carbon boat in the furnace could balance the carbon activity spontaneously during the reduction-carbonization process, which made the carbon diffusion rate match with the carbonization rate. The mean particle size of the composite powders was 175 nm with partly faceted, slightly elongated shape. The present method has distinct advantage of lower reaction temperature and shorter holding time over the previous methods. Furthermore, consolidation of the ultrafine WC-10Co composite powders in a sinter-HIP furnace was investigated. After consolidated, the WC-10Co alloy from the powders synthesized with the carbon boat added exhibited two-phase alloy with a homogeneous fine-grain microstructure and good combined mechanical properties of hardness 1985 ± 50 HV and fracture toughness 10.2 MPa·m1/2.

TiB2-based composites with high volume fraction of Fe-Ni as additive were fabricated by vacuum pressureless sintering. The effect of Fe-Ni addition (Fe:Ni=6:4) at different volume fractions from 20 to 35 vol% on the microstructure evolution and fracture behaviour of the TiB2-(Fe-Ni) composites was investigated. It was found that the TiB2-(Fe-Ni) composites consisted of only TiB2 and γ(Fe, Ni) phases without any brittle phases. The relative density, flexural strength and fracture toughness of the composites increased as the Fe-Ni content increased. The results indicated that the TiB2–35 vol% (Fe-Ni) composites exhibited the optimum combination of physical and mechanical properties, i.e., the relative density of 98.32%, the Vickers hardness of 8.56 GPa, the flexural strength of 1050.92 MPa and the fracture toughness of 17.75 MPa m1/2. The high fracture toughness of the TiB2–35 vol% (Fe-Ni) composite was due to an intensive coupled mechanism of the near-full density, dimple fracture of Fe-Ni phase, crack deflection, crack bridging, grain's pull-out and transgranular fracture of the TiB2 particles.