Z.W. Zhu

TiZr-base Bulk Metallic Glass with over 50 mm in Diameter

Low-cost TiZr-base bulk metallic glasses (BMGs) (Ti(36.1)Zr(33.2)Ni(5.8)Be(24.9))(100-x)Cu(x) (x=5, 7 and 9) with a maximum size of over 50 mm in diameter were developed by optimizing the alloy composition. The idea is initiated by selecting a particular microstructure comprising primary beta-Ti dendrite and amorphous phase. Afterwards, based on this composition of amorphous phase, a class of TiZr-base bulk metallic glasses was designed step by step to reach the optimum composition range. The glass transition temperature (T(g)), initial crystallization temperature (T(x)) and width of supercooled region (Delta T) of (Ti(36.1)Zr(33.2)Ni(5.8)Be(24.9))(91)Cu(9) BMG are 611, 655 and 44 K, respectively. The (Ti(36.1)Zr(33.2)Ni(5.8)Be(24.9))(91)Cu(9) BMG exhibits low density of 5.541 g.cm(-3) and high compressive fracture strength of 1800 MPa, which promises the potential application as structural materials.

Zr61Ti2Cu25Al12 metallic glass for potential use in dental implants: biocompatibility assessment by in vitro cellular responses

In comparison with titanium and its alloys, Zr61Ti2Cu25Al12 (ZT1) bulk metallic glass (BMG) manifests a good combination of high strength, high fracture toughness and lower Youngs modulus. To examine its biocompatibility required for potential use in dental implants, this BMG was used as a cell growth subtract for three types of cell lines, L929 fibroblasts, human umbilical vein endothelial cells (HUVEC), and osteoblast-like MG63 cells. For a comparison, these cell lines were in parallel cultured and grown also on commercially pure titanium (CP-Ti) and Ti6-Al4-V alloy (Ti64). Cellular responses on the three metals, including adhesion, morphology and viability, were characterized using the SEM visualization and CCK-8 assay. Furthermore, real-time RT-PCR was used to measure the activity of integrin β, alkaline phosphatase (ALP) and type I collagen (COL I) in adherent MG63 cells. As indicated, in all cases of three cell lines, no significant differences in the initial attachment and viability/proliferation were found between ZT1, CP-Ti, and Ti64 until 5d of incubation period. It means that the biocompatibility in cellular response for ZT1 BMG is comparable to Ti and its alloys. For gene expression of integrin β, ALP and COL I, mRNA level from osteoblast cells grown on ZT1 substrates is significantly higher than that on the CP-Ti and Ti64. It suggests that the adhesion and differentiation of osteoblasts grown on ZT1 are even superior to those on the CP-Ti and Ti64 alloy, then promoting bone formation. The good biocompatibility of ZT1 BMG is associated with the formation of zirconium oxide layer on the surface and good corrosion-resistance in physiological environment.

Reaction induced anomalous temperature dependence of equilibrium contact angle of TiZr based glass forming melt on Al2O3 substrate

Abstract The wetting behaviours and interface reactions in Ti32·8Zr30·2Ni5·3Cu9Be22·7/Al2O3 system were investigated using a sessile drop technique at 1073–1223 K in high vacuum. Both the equilibrium contact angles and the interface reactions largely depend on the test temperature. The equilibrium contact angle first decreases and then increases with the increase in temperature. The minimum of the equilibrium contact angle is 21° at 1143 K. The reason for the anomalous change of equilibrium contact angle is the change of the interface structure. At low temperature, the adsorption of α-Ti solid solution at the interface and the formation of Ti0·5Zr0·5O0·33 in the precursor film are beneficial to the wettability. With further increasing the temperature to 1173 K, the formation of ionic α-BeO is responsible for the deterioration in wettability.