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In this article, osteoblast activity on two functionalised hydroxyapatite (HA) and hydroxyapatite/ collagen (HAzCOL) surface layers is studied, and the effects of the concentrations of collagen and the collagen adding method on osteoblast activity are investigated. The morphology and elements of the HA and HAzCOL on porous titanium are observed using a scanning electron microscope and an energy dispersive spectrometer. The number of living osteoblasts is found by comparing the optical density value against a control group. The experimental results showed that osteoblasts have different responses at HA and HAzCOL surfaces that have different chemical compositions. The different concentrations and the means of collagen addition can all significantly improve the survival rate of the osteoblasts, but a 7 mg mL 21 concentration of the added amount of collagen in cell activity gives the best result. It can be concluded that collagen molecules deposit on the HAcoating uniformly and provide a favourable position for the osteoblasts.

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The influence of phase transformation conditions (a/b solution treatment plus aging, b solution treatment plus aging, and b solution treatment plus duplex aging) on the microstructure and tensile properties of Ti-3Al-15Mo-3Nb-0.2Si alloy was studied. Microstructure observation indicates that the primary a phase, which formed during a/b solution treatment, can effectively limit the growth of the b grains. The alloy was heat treated in the a/b solution, which together with aging, formed smaller grains and finer precipitates in the sample and showed good tensile ductility with a 15% elongation. Aging temperatures from 450 to 600°C were used to study the effects of aging treatment on the alloyÕs microstructure and tensile properties. Precipitation phases appeared in particular positions (a GB , a WGB , and a WM ) during the aging process which depended on phase transformation conditions and caused variations in the alloyÕs tensile properties. The alloy treated by duplex aging after b solution had a higher ultimate tensile strength at 1370 MPa than that of other samples, resulting from the finer a precipitates transformed from the x phases. The relationship of tensile properties and phase transformation was investigated by observing the material fracture, and small and dense dimples were seen in the tensile specimen treated by a/b solution plus aging treatment which led to excellent ductility. Deep dimples in the duplex aging specimen resulted in beneficial high strength.