Tensile behavior of TiB-reinforced Ti matrix composites with different titanium powders

Abstract

Although titanium alloys are known to possess low density, high specific strength, and excellent corrosion resistance, their low specific stiffness and wear resistance have restricted their widespread application. Cost-effective discontinuously reinforced titanium and its alloys containing titanium boride (TiB) are emerging as possible candidates for overcoming these limitations. The mechanical properties of titanium matrix composites (TMC) are mainly dependent on the matrix composition, and on the volume fraction, and distribution of reinforcements. The distribution of reinforcements in the matrix depends on the particle shape and size of the Ti matrix powder. The purpose of this study was to investigate the effect of Ti powders produced by different manufacturing processes on the tensile behavior of titanium compacts and TiB reinforced Ti matrix composites (TiB/Ti). The Ti powders were produced by the hydride-dehydride (HDH) or the gas atomization (GA) process with particle sizes of <45 μm and <150 μm. The TiB/Ti composites were produced by a spark plasma sintering process. The Ti compact using Ti particle sizes of <45 μm, with higher oxygen content, possessed high tensile strength. This is because of the influence of oxygen as an interstitial strengthening element in the titanium alloy, which is well known. The TiB/Ti composites using HDH Ti powder with a particle size of <45 μm had the highest Young's modulus, tensile strength, and Vickers microhardness. For the HDH Ti powder with a particle size of <45 μm, small TiB clusters connected like a network were uniformly distributed around the Ti matrix particles. Cracks in the composites initiated at the TiB clusters when a tensile load was applied to the composites. The presence of small TiB clusters inhibited the formation of cracks.