Research On The Mixed Salt Method Fabrication And Mechanical Properties Of TiB₂/Al Composites

In this paper, aluminum matrix composites reinforced with T1B2particles was synthesized by the LSM(London Scandinavian Metallurgical).The synthesis mechanism and microstructure of TiB2/Al composite materials were systematically studied. Also, the mechanical properties of composites were analyzed. Additionally, the microstructure evolution rule of the composites with different content of TiB2and the composites with different addition of rare earth elements were discussed. The results of TiB2/Al composite materials has guiding significance in industrial production. The specific research work are as follows:(1) TiB2/Al composite materials with different content of TiB2were fabricated at850℃using KBF4-K2TiF6system. The phase composition, microstructure, size of the particulate and hydrogen ion content were investigated by Optical Microscope(OM), Scanning Electronic Microscope(SEM), X-ray diffraction(XRD), Oxygen nitrogen hydrogen analyzer. The results show that the prepared composites with different content of TiB2do not contain brittle phase of TiAl3, and the in-situ TiB2particles exist stably in the composites; Furthermore, both the size of TiB2particles and the hydrogen ion content increase with the mass fraction of TiB2particles growing. The particles are small size and distribute uniformly in the matrix when the particle mass fraction are5%and10%, while the size of particles are large in the TiB2/AI composites when the particle mass fraction are15%and20%. The heat treatment would decrease the hydrogen ion content effectively,especially for the TiB2/Al composites with the TiB2mass fraction at5%and10%.(2) For the TiB2/Al composites with5%content of particles, the effect of rare earth on the composites were analyzed by adding0.3%different rare erath element with LSM process. It indicates that the addition of different rare earth elements can refine TiB2particle and improve the wetting ability between particle and aluminum liquid. What’s more, it can restrain TiB2particle from agglomerating and getting large, and the addition of0.3%Sc rare earth element can best refine TiB2particle. The rare earth element in liquid aluminum can easily conglomerate at solid-liquid interface, thereby reducing the tension between the interface, which is the important reason that the wetting ability between particles and liquid aluminum improved.(3) Electronic universal testing machine and friction and wear tester are used to test the tensile properties and wear properties of the prepared TiB2/Al composites. Also, the tensile fracture morphology and grinding crack morphology after wear analyzed, the tensile data of TiB2/Al composite materials are verified by Abaqus software simulation. The results show that the addition of0.3%Sc rare earth element can best improve tensile strength, which can get152MPa. The addition of0.3%Er rare earth element is the best for improving the composite elongation, which can be17.2%. Moreover, the results of dry sliding friction and wear performance test at room temperature show that10%-TiB2/Al composite gets best wear resistance. The wear mechanism of the composites is abrasion and oxidation at low load. Meanwhile, the composites exhibit characteristics of adhesion wear and slight abrasive wear with the load increasing.