Strengthening Mechanism of Titanium Boride Whisker-Reinforced Ti-6Al-4V Alloy Matrix Composites with the TiB Orientation Perpendicular to the Loading Direction.

Hiroki Kurita,Fumio Narita,Sophie Gourdet,Shiori Suzuki,Noriharu Yodoshi,Shoichi Kikuchi

doi:10.3390/ma12152401

Abstract

We fabricated fully dense titanium boride (TiB) whisker-reinforced Ti-6Al-4V alloy matrix (Ti6Al4V-TiB) composites, with a homogeneous dispersion, a TiB orientation perpendicular to the loading direction (; two-dimensional random direction) and an intimate Ti/TiB interface without an intermediate interfacial layer in the Ti-6Al-4V alloy matrix, by spark plasma sintering. Microstructural analysis allows us to present the tensile properties of the Ti6Al4V-TiB composites with the theories for discontinuous fiber-reinforced composites. The Ti6Al4V-TiB 10 vol.% composite yielded a Young’s modulus of 130 GPa, an ultimate tensile strength (UTS) of 1193 MPa and an elongation of 2.8%. The obtained experimental Young’s modulus and UTS of the Ti6Al4V-TiB composites were consistent with the theoretical values estimated by the Halpin-Tsai and Shear-lag models. The good agreement between our experimental results and these models indicates that the TiB whiskers behave as discontinuous fibers in the Ti-6Al-4V alloy matrix.

Highlights

Titanium (Ti) alloys are widely used as aerospace materials due to their high specific strengths and corrosion resistance
We evaluated the tensile properties of these Ti6Al4V-titanium boride (TiB) composites and compared them with the theoretical values estimated by the equations for discontinuous fiber-reinforced composites to reveal their strengthening mechanism
We fabricated fully dense Ti6Al4V-TiB composites by SPS. These Ti6Al4V-TiB composites had a homogeneous dispersion of TiB whiskers in a Ti-6Al-4V alloy matrix

Summary

Introduction

Titanium (Ti) alloys are widely used as aerospace materials due to their high specific strengths and corrosion resistance. Among the available Ti materials, Ti matrix composites (TMCs) have attracted the most attention due to their potential for possessing higher specific mechanical properties than conventional Ti alloys [1,2]. It has been reported that titanium boride (TiB) whiskers can be formed in Ti alloys by the following chemical reaction: Ti + TiB2 → 2TiB. Materials 2019, 12, 2401 and that these TiB whiskers are chemically stable in the Ti alloys [1,2]. It seems that the slight difference in the thermal expansion coefficient between TiB (7.15 × 10−6 K−1 ) and

Methods

Results

Conclusion