Effects of chromium addition on structure and mechanical properties of Ti-5Mo alloy

Titanium and its alloys have been widely used as biometals due to their excellent biocompatibility, corrosion resistance and moderate mechanical properties. As-cast Ti-5Mo and a series of Ti-5Mo-xCr (x = 1, 2, 3, 4, 5, 7 and 9 mass%) alloys were designed and fabricated for the first time to develop novel biomedical materials. Commercially pure titanium (c.p. Ti) was used as a control. The experimental results indicated that the structure and mechanical properties of these alloys changed as different amounts of Cr were added. The Ti-5Mo alloy was composed mainly of alpha' phase. When 1 mass% Cr was added, the structure was changed to alpha" phase. The addition of 3 mass% or greater Cr content resulted in beta-phase Ti-5Mo-xCr alloys. x phase formed in alloys containing 3-5 mass% Cr. The largest quantity of x phase and highest bending modulus were found in Ti-5Mo-3Cr. With the exception of x-phase Ti-5Mo-3Cr and Ti-5Mo-4Cr, the Ti-5Mo-xCr and Ti-5Mo alloys had good bending ductility. alpha"-phase Ti-5Mo-1Cr had the highest bending strength/modulus ratio (23.4). This ratio is higher than that of c. p. Ti (8.5) by 175% and the Ti-5Mo alloys (20.3) by 15%. The elastic recovery angle of the Ti-5Mo-1Cr (28.4 degrees) was about 10.5 times greater than for c.p. Ti (2.7 degrees). In the search for a better implant material, alpha"-phase Ti-5Mo-1Cr, with its low modulus, ductile property, excellent elastic recovery capability, and reasonably high strength, is a promising candidate. (C) 2014 Elsevier Ltd. All rights reserved.