On The Ternary Tungsten-Chromium System: Sintering, Microstructure, And Phase Diagram

To study the ternary phase diagram of the tungsten manganese-chromium system, four different alloys were prepared by mechanical alloying and sintered at various temperatures from 1,225 degrees C to 1,425 degrees C. From X-ray diffraction (XRD) patterns, the main phases present were a tungsten (bcc) phase and a chromium (bcc) phase. Other phases present were topologically close packed phases and oxides. Scanning electron microscopy (SEM) images of the micro-structure depicted three distinct metallic phases: a tungsten-rich phase, chromium-rich phase, and a phase that was a liquid sometime during processing. These results were interpreted with the assistance of calculated ternary sections of the tungsten-manganese-chromium system. The major discrepancy between the results and the calculated phase diagrams was the appearance of topologically closed-packed (TCP) phases. The sintering behavior for these samples was consistent with transient liquid-phase sintering.