Hot-pressing mixed carbides of ta, hf, and zr.

Abstract

The effect of hot-pressing parameters (temperature, pressure, and time) on the density and grain size of two mixed carbides, 80% TaC 20% HfC and 80% TaC 20% ZrC (nt.%), was investigated. The purpose of the investigation was to determine what conditions would be necessary to produce high-density bodies and what resultant grain size might be expected for a given set of conditions. The hotpressing was accomplished by means of an inductively heated graphite die body with pressure being supplied by a hydraulic press. Based on the computed theoretical densities, 4TaC . 1HfC was hot-pressed to approximately 100% relative density nt 4800 deg F and 8000 psi in 15 minutes. The maximum density achieved in the 4TaC. 1ZrC composition was 96% relative density under the same conditions. Based on grain size measurements there is evidence of a recrystallizntion temperature for both materials at about 4600 deg F under a hot- pressing pressure of 3700 psi. (auth)