Probing the texture transition sequence of near β titanium matrix composites by observing the uneven hot deformation microstructure

Abstract

This study is focused on the sequence of texture transformation and uneven microstructure evolution during hot compression of 2 vol% TiC/Ti-4Al-1Sn-2Zr-5Mo-8 V-2.5Cr composites. After hot compression, the uneven microstructures, including local high deformed region (HDR) and low deformation region (LDR), are observed by EBSD. The area and width of elongated grains decrease in the HDR, but the LDR shown the opposite trend as temperature and deformation rate rise. The sequence of texture transformation with different lattice rotation axis during hot compression of TMCs is established based on lattice rotation during continuous recrystallization (CDRX). At a low temperature (850 °C), initial as-cast (110)//CD (ζ fiber) texture first changes to (111)//CD (γ fiber) texture, and then stable (001)//CD texture (θ fiber: {001} 〈0−10〉). The rotation axis is the 〈110〉 direction on the {001} plane. Low-temperature stable (001)//CD texture can be further changed into near-(110)//CD with varied rotation axis of 〈111〉 direction on the {110} plane if the deformation temperature is sufficiently high and strain rate is low (for instance, at 940 °C with 0.001 s−1). Meanwhile, the effect of TiC particles on β matrix texture is limited, and an orientation relationship of [−1−11]β//[−1−10]TiC1¯1¯1β//1¯1¯0TiC is identified between TiC particles and the β matrix.