Lower sintering temperature tungsten alloys for space research

In the early 1900s the sintering temperature for tungsten was 2800 degrees C or higher. At that time direct electrical discharge (self-heating) was used to induce sintering densification. A reduced sintering temperature for tungsten arose in forming radiation containment structures. By 1938 the sintering temperature was 1500 degrees C for tungsten alloyed with Ni-Fe or Ni-Cu using liquid phase sintering. Activated sintering arose between 1946 and 1961, relying on low concentrations of Pd, Pt, Ni, or other late transition metal additions, enabling densification at temperatures in the 1200 to 1400 degrees C range. In 1991, W-Ni-Mn alloys were identified and became the precursor to W-Ni-Cu-Mn alloys that densify at 1200 degrees C, a temperature associated with steel sintering. The lower sintering temperature W-Ni-Cu-Mn system is now critical to research on microgravity processing (densification, distortion, and coarsening) since it matches with furnace capabilities on the International Space Station. Details on the experiments are given in this article. (C) 2015 Published by Elsevier Ltd.