Ti-based Bulk Metallic Glasses for Biomedical Applications

Biomedical materials can improve the life quality of a number of people each year. The range of applications includes such as joint and limb replacements, artificial arteries and skin, contact lenses, and dentures. So far the accepted biomaterials include metals, ceramics and polymers. The metallic biomaterials mainly contain stainless steel, Co-Cr alloys, Titanium and Ti-6Al-4V. Recently, bulk metallic glasses as novel materials have been rapidly developed for the past two decades in Mg-, Ln-, Zr-, Fe-, Ti-, Pd-, Cu-, Ni-based alloy systems because of their unique physical, chemical, magnetic and mechanical properties compared with conventional crystalline alloys. Metallic glass formation is achieved by avoiding nucleation and growth of crystalline phases when cooling the alloy from the molten liquid. Therefore, the different atomic configurations induced significantly different characteristic features such as high strength, good corrosion resistance and excellent electromagnetic properties, which are from their crystalline counterparts. Among different bulk metallic glasses, Ti-based bulk metallic glasses are expected to be applied as biomedical materials due to high strength, high elastic limit, low Young’s modulus, excellent corrosion resistance and good bioactivity of Ti element. Many Ti-based metallic glasses have been developed in Ti-Cu-Ni, Ti-Cu-Ni-Co, Ti-Cu-Ni-Zr, Ti-Cu-Ni-Zr-Sn, Ti-CuNi-Sn-B-Si, Ti-Cu-Ni-Sn-Be, Ti-Cu-Ni-Zr-Be, Ti-Cu-Ni-Zr-Hf-Si and Ti-Cu-Ni-Zr-Nb (Ta) alloys, based on the Inoue’s three empirical rules (Inoue, 1995) i.e., 1) multi-component consisting of more than three elements, 2) significant atomic size mismatches above 12% among the main three elements, and 3) negative heats of mixing among the main elements.