P.H. Tsai

Microalloying effect of Si on mechanical properties of Ti based bulk metallic glass

The (Ti40Zr10Cu36Pd14)100 − xSix (x = 0, 0·5, 1·0, 1·5) bulk metallic glass (BMG) rods with a diameter of 2–4 mm have been successfully fabricated by suction casting method and characterised. The X-ray diffraction results reveal that these entire (Ti40Zr10Cu36Pd14)100 − xSix alloy rods exhibit a typical amorphous diffraction pattern with only a broad maximum at 2θ∼40°. The optimum glass forming ability values γ and γm (0·430 and 0·774 respectively) occur at the (Ti40Zr10Cu36Pd14)99·5Si0·5 amorphous alloy. This suggests that the Si element present a positive effect on increasing glass forming ability in the Ti40Zr10Cu36Pd14 alloy system. The hardness of these Ti based BMGs exhibits an increasing trend with Si addition and saturated ∼710 HV. In addition, the result of compression test shows that the optimum mechanical property occurs at the (Ti40Zr10Cu36Pd14)99·5Si0·5 amorphous alloy, which presents 2050 MPa fracture strength and 8% failure strain.

Biocompatibility study on Ni-free Ti-based and Zr-based bulk metallic glasses

Safety and reliability are crucial issues for medical instruments and implants. In the past few decays, bulk metallic glasses (BMGs) have drawn attentions due to their superior mechanical properties, good corrosion resistance, antibacterial and good biocompatibility. However, most Zr-based and Ti-based BMGs contain Ni as an important element which is prone to human allergy problem. In this study, the Ni-free Ti-based and Zr-based BMGs, Ti40Zr10Cu36Pd14, and Zr48Cu36Al8Ag8, were selected for systematical evaluation of their biocompatibility. Several biocompatibility tests, co-cultural with L929 murine fibroblast cell line, were carried out on these two BMGs, as well as the comparison samples of Ti6Al4V and pure Cu. The results in terms of cellular adhesion, cytotoxicity, and metallic ion release affection reveal that the Ti40Zr10Cu36Pd14 BMG and Ti6Al4V exhibit the optimum biocompatibility; cells still being attached on the petri dish with good adhesion and exhibiting the spindle shape after direct contact test. Furthermore, the Ti40Zr10Cu36Pd14 BMG showed very low Cu ion release level, in agreement with the MTT results. Based on the current findings, it is believed that Ni-free Ti-based BMG can act as an ideal candidate for medical implant.