Microstructure and compressive properties of in situ synthesized (TiB + TiC)/Ti composites

Abstract

TiB and TiC reinforced titanium matrix composites have been produced by non-consumable arc-melting technology utilizing the self-propagation high-temperature synthesis reactions between titanium and B4C, graphite. X-ray diffraction (XRD) was used to identify the phases in the composites. Microstructures of composites have been observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The results show that there are three phases in the composite: TiB, TiC and titanium matrix alloy. Reinforcements are distributed uniformly in the matrix. TiB grows in short-fiber shape and TiC grows in dendritic, equiaxed shapes. The interfaces between reinforcements and titanium matrix alloy are very clean. There is no any interfacial reaction. There are high-density dislocations around TiC particle. Mechanical properties have been improved due to the incorporation of reinforcements. The addition of aluminum not only strengthens the titanium matrix alloy by solid solution strengthening, but also improves the mechanical properties of composites by refining the reinforcements and matrix alloy.