Near-net-shape Tungsten-Rhenium Alloy Parts Produced by Shrouded Plasma Spray Forming

Abstract

W-5% (mass fraction) Re composite powder was fabricated by a new cladding method. W-5%Re nozzles used for solid rocket motor (SRM) were produced by shrouded plasma spray forming (PSF). The change regularity with the sintering time for the compact density, structure, micro-hardness, tensile strength and compression strength of the nozzel under 2300 ℃ vacuum sintering was studied. The study result indicates that the lamellae structure, and vertical columnar grains, micron-sized pores and rough interlamellar contacts with gaps of sub-micron sizes between lamellaes are found in PSF deposits. The relative density, micro-hardness, ultimate tensile strength (UTS) and compressive strength of PSF deposits are 87.5 %, 321.4 HV0.025, 57.9 MPa and 390.2 MPa respectively. With the sintering time prolonged from 2 h to 6 h and 8 h, the relative density and mechanical properties of W-Re alloy parts increase with the initial lamellar structure transformed into granular structure.After vacuum sintering for 8 h, the relative density, micro-hardness, UTS, compressive strength and yield strength increase to 98.6 %, 529.7 HV0.025, 384.7 MPa, 1466.5 MPa and 879.6 MPa respectively. For the addition of Re element, the recrystallization temperature and grain size of W-Re alloy are improved and effectively refined respectively. Thus, the strength and plasticity of the alloy can be improved remarkably, and the Re effect is revalidated and double checked in W-Re alloy fabricated by PSF and Vacuum sintering.

Keywords

• W-Re alloy part
• shrouded plasma spraying
• near-net-shape
• vacuum sintering
• mechanical property