Tribological Properties Of Ti-based Dendrite-reinforced Metallic Glass Matrix Composites

The amorphous alloy was obtained by restraining the orderly arrangement of the metal atoms at molten state by rapid cooling, which was completely different from that of traditional metal. Bulk metallic glasses exhibit superior performance at ambient temperature, such as high strengths, large elastic limits, higher corrosion resistance, high abrasion resistance and excellent magnetic properties and so on. Therefore, more attention was attracted from the orderly structure to the amorphous substance, leading to the vigorous development of amorphous and condensed matter physics. However, the amorphous alloys exhibited brittle fracture behavior at room temperature, which greatly limits its application of engineering. Consequently, a series of dendrite-reinforced metallic glass matrix composites were developed by adjusting the composition and using appropriate cooling process. This new composites possessed have both high strength and excellent toughness, so that it had a wider range of engineering applications.In this paper, three Ti-based bulk amorphous alloys with different components of Ti₄₂Zr₂₂V₁₄Cu₅Be₁₇, Ti46Zr20V12Cu5Be17 and Ti48Zr18V12Cu5Be17 were prepared using arc melting and copper mold suction casting, respectively. The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti₄₂Zr₂₂V₁₄Cu₅Be₁₇) were analyzed at different normal load under the dry condition and rainwater. The wear mechanisms and corrosion mechanism of the composites in the acid rain were explored. Besides, the effect of the volume fraction of the crystalline phase on micro-hardness, corrosion resistance, friction and wear behavior of Ti-based bulk metallic glass matrix composites was investigated. The results showed that:1. The average value of the frictional coefficients and friction fluctuations were proportional to the load. The wear mechanisms of composites were mainly adhesive wear accompanied by abrasive wear under the dry condition. Meanwhile, obvious work hardening was produced on the surface of the grinding crack. The greater load the more work hardening was.2. However, both the frictional coefficients and wear rate of the composite in the rain water were larger than that under the dry condition, primarily owing to the corrosion of chloride ions on the worn surface. It was obvious that there were large delamination and many flake-like debris in the wear track under the rain water, which revealed the characteristics of the corrosion wear.3. The electrochemical test results showed that the surface of samples was pitting corroded by the chloride ions under the environment of rain water, and the matrices were corroded preferentially, and then, the dendrites were exposed, leading to the easier damage to the surface of the samples more likely to be damaged.4. It was also found that the hardness, wear resistance and corrosion rate of the dendrite-reinforced metallic glass matrix composites were increased with the increasing of volume fraction of the crystalline phase. Furthermore,during the sliding,both softening of amorphous matrix and hardening of branches crystal occurred at the same time. Therefore, the higher work hardening rate was obtained with appropriate volume fraction of the crystalline phase.