Structural-Phase State and Mechanical Properties of a Laser Cladding Titanium Matrix Composite Based on Ti64 Alloy and TiB2 Ceramics

The paper presents experimental studies on laser cladding synthesis of a titanium matrix composite based on Ti64 titanium alloy and TiB₂ ceramic reinforcement. The weight percentage of TiB₂ ceramics in the composite was 5, 10 and 15%. The phase composition of the resulting materials was analyzed by standard X-ray diffraction and synchrotron X-ray diffraction. It was found that the structure of the titanium matrix composite with 5 wt % ceramics consists of TiB nanowhiskers, and that of samples with higher ceramic content exhibits TiB whiskers with a width of several micrometers. The addition of TiB₂ ceramics increases Young’s modulus, nano- and microhardness of composite samples compared to Ti64 alloy. The indentation method was used to study the formation of a phase that is different from TiB₂ ceramics and TiB microwhiskers and has elastic properties exceeding the elastic properties of the original Ti64 matrix phase. Analytical predictions showed an increase in the effective elastic properties of the formed heterogeneous material with the predicted new phase. It was also found that a lower friction coefficient can be achieved by forming a structure with nanowhiskers, while higher Young’s modulus and microhardness can be obtained by forming a structure with microwhiskers.