Abstract
In-situ TiB/TiC particle-reinforced titanium matrix composites (TMCs) based on a near-β Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) were synthesized by solid-state reaction with B4C and graphite particles during spark plasma sintering (SPS). In this study, investigations were focused on the influence of the molar TiB:TiC ratio on the mechanical properties of the composites. With respect to the adjustment of the molar TiB:TiC ratio, the formation of stoichiometric TiC or nonstoichiometric TiCy was considered as the literature provides conflicting information in this respect. Furthermore, the solid-state reaction behavior influenced by the matrix alloying elements is discussed in comparison to a pure titanium matrix. The hardness, compressive strength and bending strength of the TMCs were improved successfully due to the TiB and TiC particles maintaining acceptable levels of ductility. However, X-ray diffraction experiments revealed that for the adjustment of the molar TiB:TiC ratio, the stoichiometry of the TiCy particles formed must be considered as nonstoichiometric TiC0.5 resulted from the solid-state reaction of carbon and titanium. Compared to TMCs with pure titanium matrices, more sluggish solid-state reaction kinetics were observed. This was attributed to the matrix alloying elements molybdenum, vanadium and chromium, which formed solid solutions within the reinforcing particles.
Highlights
In recent decades, materials research has increasingly focused on the development of titanium matrix composites (TMCs) due to their outstanding properties—combining high specific strength, specific stiffness, and hardness with heat- and/or corrosion resistance [1,2,3,4]
B4C particles presented in Figure exhibited anwhile angular shape, while the consisted of large particles a highparticles aspect ratio length ratio and thickness, fine, flake-shaped graphite powder consistedwith of large withbetween a high aspect between and length and thickness, particles were partly arranged clusters, Figure
A thin TiCy reaction layer was formed between these graphite particles and the adjacent CP-Ti or Ti-5Al-5Mo-5V-3Cr alloy (Ti-5553) particles
Summary
Materials research has increasingly focused on the development of titanium matrix composites (TMCs) due to their outstanding properties—combining high specific strength, specific stiffness, and hardness with heat- and/or corrosion resistance [1,2,3,4]. An effective method for improving the properties of titanium or titanium alloy-based composite materials is their reinforcement through the introduction of ceramic particles. In-situ particle reinforced metal matrix composites (MMCs) exhibiting excellent mechanical properties owing to the formation of stable ceramic reinforcements during processing are reported in the literature including a wide range of matrix materials like titanium, aluminum, copper, nickel or iron along with borides, carbides, oxides and nitrides [5].
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