Study on microstructure and properties of TiBw/Ti-V-Al light weight high temperature shape memory composite

Abstract

This study investigated a novel light weight high temperature shape memory composite with a quasi-continuous network microstructure, which greatly promoted to the application of shape memory alloy in aerospace. In-situ TiB whisker was introduced and mainly distributed along the large Ti-V-Al matrix, which contributed to the breakthrough of the mechanical properties. No obvious influence on the martensite structure, and the spear-like martensite variants still exhibited the typical self-accommodation morphology with {011} type I twin relationship. The XRD results showed that the phase constitution gradually evolved from sole α″ phase to the coexistence of the α″ phase and β phase with the increasing of TiB2 contents. The reverse martensitic transformation peak temperature increased firstly and then decreased with the increasing of TiB2 contents, owing to the influence of composition variation and stress field. It was noteworthy that the TiBw/Ti-V-Al composite with 2.0 wt% TiB2 addition exhibited a higher strength, accompanied by the superior elongation (15.7%) and high martensitic transformation temperature. The yield strength and fracture strength were 692 MPa and 932 MPa, respectively. In addition, the shape memory effect increased firstly and then decreased with the increasing of the TiB2 contents. The maximum recoverable strain of 4.4% with 6% pre-strain can be gained in 0.3 wt%TiB2 added Ti-V-Al composite.