Low-temperature fabrication of dense, near net-shaped tungsten/zirconium carbide composites with tailored phase contents by the prima-DCP process

Refractory metal/carbide composites can possess unique and attractive combinations of properties for aerospace and other applications. A novel process for fabricating dense, near net-shaped refractory metal/carbide composites at modest temperatures has recently been demonstrated: the PRIMA-DCP process (Pressureless Reversible Infiltration of Molten Alloys by the Displacive Compensation of Porosity). In this paper, the PRIMA-DCP process is used to synthesize W/ZrC-bearing composites with tailored phase contents. Porous, but rigid WC-bearing preforms were pressureless infiltrated with a Zr-Cu liquid at 1200-1300degreesC. Upon infiltration, the Zr in the liquid underwent a displacement (oxidation-reduction) reaction with WC to yield a solid mixture of ZrC and W. The reaction-induced increase in internal solid volume was accommodated by the prior pore volume of the rigid preform ("displacive compensation of porosity"). As the solid products filled the pores, the unreacted liquid was extruded back out of the preform ("reversible infiltration"), so that dense composites were produced with little change in the external dimensions. By varying the W:WC ratio of the preforms, composites with tailored phase contents (i.e., varied amounts of ZrC) could be produced.