The impact of matrix texture and whisker orientation on property anisotropy in titanium matrix composites: Experimental and computational evaluation

Abstract

In order to understand the relationship between microstructure and mechanical property as well as provide new guidance for composites design, the impacts of matrix texture and TiB whisker orientation on anisotropy of mechanical properties in hot-rolled titanium matrix composites (TMCs) were investigated by experimental and computational methods. The results show that the matrix contains a strong transverse type (T-type) texture due to the superposition of deformation texture and transformation texture. TiB whiskers aligned along the rolling direction (RD) enhance the intensity of the 112‾0 fiber texture in the matrix due to their special orientation relationship with matrix alloy ([112‾0]α−Ti∥[020]TiB). Significant variations in elastic modulus, yield strength and ductility are all noted, depending on the orientation of the tensile axis with respect to the basal of matrix texture and whisker axis. These property anisotropies were further quantified and corroborated numerical models as a function of matrix texture and whisker orientation. Specifically, T-type matrix texture results in a lower modulus and yield strength but a higher ductility in RD. However, the aligned whiskers lead to higher modulus, yield strength and ductility in RD. The strengthening contribution from aligned TiB whiskers decreases rapidly with cos4α with increasing off-axis angle (α). Moreover, the modeling results predict that the TiB whiskers would undergo fracture if the aspect ratio exceeds ARc/cos2α; otherwise, the interfacial debonding would occur.