Effects of volume fraction on the microstructure and tensile properties of in situ TiBw/Ti6Al4V composites with novel network microstructure

In order to better understand the relationship of structure–mechanical properties of TiBw/Ti6Al4V (TiBw/Ti64) composites with a network microstructure and deduce the upper limit of TiBw volume fraction, the effects of volume fraction on the microstructure and tensile properties were further investigated. The equation calculating the optimal and maximum volume fractions of reinforcement for the composites with a network microstructure was deduced. For the present system, the optimal and maximum volume fractions were verified to be 5.1 vol.% and 10.2 vol.%, respectively, by calculation, microstructure observation, tensile properties. When the volume fraction was equal and lower than 5.1 vol.%, the coarse TiBw formed, or else, the fine TiBw, the cluster TiBw and the block TiBw, even unhealed pores formed. The tensile strength of TiBw/Ti64 composites increases and then hastily decreases, while the ductility keeps on decreasing with increasing volume fractions of TiBw reinforcement.