Enhanced thermal stability of W-25Re/Ti/carbon-carbon composites via gradient diffusion-bonding

Abstract

A carbon-carbon (C-C) composite was joined with a W-25Re alloy through a Ti interlayer using the diffusion-bonding technique. The stacked components were hot-pressed with an applied pressure of 25 MPa at 1600 °C for two hours. The cross-sections of the joints were investigated to examine the intermediate phase and elemental distribution near the Ti interlayer. It was confirmed that tungsten, rhenium, and carbon diffused into the Ti interlayer to form various intermediate phases; as a result, the joining interface remained stable through the gradient distribution of the intermeditate phases. The Ti interlayer was divided into two regions according to the diffusion range, and the Ti reacted with the carbon that had rapidly diffused from the C-C composite to generate precipitates. To evaluate the high-temperature durability of the joint interface, a thermal stability test was conducted at 2000 °C in an Ar atmosphere. The diffusion of the components accelerated at high temperatures, forming various solid solution phases (W(Re)-Ti and W-25Re-Ti) and metal carbide phases ((W,Ti)C1−x and TiC) in the expanded interfacial region.