Effect Of Thermo-mechanical Processing On Microstructure And Mechanical Properties Of In Situ Ti Matrix Composites

Recently, titanium matrix composites (TMCs) attracted more and more attention because of their high strength and elastic module compared to their weight, especially their good mechanical properties at elevated temperature. On the other hand, with the incorporation of reinforcements, due to the distribution of the hard ceramic particles on the soft matrix, the machining property of TMCs is poor, which is an unfavorable factor for the material to be used widely. Furthermore, compared to traditional materials, it is a more complex subject to control the microstructure of TMCs reinforced by whiskers or by particles due to the incorporation of reinforcements. For the TMCs reinforced by particles, many research have been done on the action between reinforcements and matrix. But the subject on the matching relationship between reinforcements and the microstructure of matrix has not been studied yet. The mechanical properties of TMCs are dependent on the reinforcements properties, the reinforcements size, the reinforcements volume fraction and the reinforcements distribution. The microstructure of matrix also has effect on the mechanical properties of TMCs, so it is also an important subject to study the effect of matrix microstructure on the TMCs for the fabrication of high properties of TMCs.At present, TiC and TiB are the most used reinforcements for in situ TMCs. Base on this, in this work we prepared in situ TiC or (TiB+TiC)/Ti-1100 composites with various volume fraction of reinforcements by the consumable vacuum arc melting. The microstructure of composites and reinforcements were investigated using optical microscopy, Scanning Electronic Microscope (SEM), X-Ray Diffractometer (XRD) and Transmission Electronic Microscope (TEM). Then, theβtransus temperature of the in situ composites are measured by metallographic method, and the mechanism of the residual reaction material on theβtransus temperature of the in situ composites has been investigated. The hot deformation behavior of the in situ TiC or (TiB+TiC)/Ti-1100 composites was investigated by means of iso-thermal compression at various temperatures with various deformation rate. The composites were thermomechanical processed with various parameters, and the microstructure evolution of the composites during various thermomechanical processing was...