Synthesis of Ti–Sn–Nb alloy by powder metallurgy

The microstructural evolution and characteristics of the Ti–16Sn–4Nb powder particles and bulk alloys sintered from the powders ball-milled for various periods of time were studied. Results indicated that ball milling to 8 h led to the development of a supersaturated hcp α-Ti and partial amorphous phase due to the solid solution of Sn and Nb into Ti lattice. The bulk Ti–16Sn–4Nb alloy made from the powders ball milled for a short time, up to 2 h, exhibited a primary α and a Widmanstätten structure consisting of interlaced secondary α and β. With an increase in ball milling time up to 10 h, the microstructure evolved into a fine β phase dispersed homogeneously within α phase matrix. The microhardness values of the bulk alloy in both α- and β-phases increased with the increasing of the ball milling time and reached a plateau value at 8 h and longer, i.e. 687 and 550 HV for α- and β-phases, respectively. Likewise, the microhardness of the α phases was always higher than that of the β phases in the bulk alloys made from the powders ball milled for the same milling time.

Preparation of bioactive porous titanium-molybdenum alloy through powder metallurgy

Porous Ti-Mo alloy samples with different porosities from 52% to 72% were successfully fabricated by the space-holder sintering method. The pore size of the porous Ti-Mo alloy samples were ranged from 200 to 500 μm. The plateau stress and elastic modulus of the porous Ti-Mo alloy samples increases with the decreasing of the porosity. Moreover, an apatite coating on the Ti-Mo alloy after an alkali and heat treatment was obtained through soaking into a simulated body fluid (SBF). The porous Ti-Mo alloy provides promising potential for new implant materials with new bone tissue ingrowth ability, bioactivity and mechanical properties mimicking those of natural bone.

Novel metal structures through powder metallurgy for biomedical applications

Biocompatible porous Ti-16Sn-4Nb alloys were synthesised in quest of a novel tissue engineering biomaterial for bone regeneration. The alloys were prepared from elemental powders via mechanical alloying followed by space-holder sintering. The effects of ball milling variables on the characteristics and mechanical properties of bulk and porous Ti-16Sn-4Nb alloy have been investigated.

Porous Ti-Nb-Zr alloy through powder metallurgy for biomedical applications

This work investigated the structure and properties relationship, surface modification, biocompatibility and bioactivity of a porous Ti-Nb-Zr alloy. The porous alloy exhibited inter-connected porous structure, good biocompatibility and high mechanical strength with an elastic modulus close to that of bone. Porous Ti-Nb-Zr alloys are thus promising biomaterials for hard tissue replacement.

Anisotropic mechanical properties of nickel foams fabricated by powder metallurgy

In the present study, porous nickel foam samples with pore sizes of 20 μm and 150 μm and porosities of 60 % and 70 % were fabricated by the space-holding sintering method via powder metallurgy. Electron scanning microscopy (SEM) and Image-Pro Plus were used to characterise the morphological features of the porous nickel foam samples. The anisotropic mechanical properties of porous nickel foams were investigated by compressive testing loading in different directions, i.e. the major pore axis and minor pore axis. Results indicated that the nominal stress of the nickel foam samples increases with the decreasing of the porosity. Moreover, the foam sample exhibited significantly higher nominal stress for loading in the direction of the major pore axis than loading in direction of the minor pore axis. It is also noticeable that the nominal stress of the nickel foams increases with the decreasing of the pore size. It seems that the deformation behaviour of the foams with a pore size in the micron-order differs from those with a macro-porous structure.

Production of a low young modulus titanium alloy by powder metallurgy

Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH) powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.

Production of Ti-35Nb alloy by powder metallurgy for aerospace application

Titanium and its alloys provide high strength-to-weight ratios, good fatigue strength and increased corrosion resistance compared with others materials. Its acceptance in aerospace has been limited by costs considerations such as high cost of raw material, high buy-to-fly ratios and expensive machining operations. Significant cost reductions can be obtained by vacuum sintering and powder metallurgy (P/M) techniques by producing near net shapes and consequently minimizing material waste and machining time. The Ti 35Nb alloy exhibit a low modulus of elasticity. Stemming from the unique combination of high strength, low modulus of elasticity and low density, this alloy is intrinsically more resistant to shock and explosion damages than most other engineering materials. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 and 1600 °C, in vacuum. Sintering behavior was studied by means of dilatometry. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Density was measured by Archimedes method. Copyright © 2004 Society of Automotive Engineers, Inc.