Influence of the high-pressure ω - Zr phase on selected properties of sintered zirconium powder materials

Most commercial zirconium alloys are obtained by melting methods and consist of α-Zr. The sintering of zirconium powders is carried out mainly by pressure methods, which is the reason for the appearance of higher stresses in the materials and the presence of the high-pressure ω-Zr phase. Sintered zirconium materials containing α-Zr, α-Zr + β–Zr + Nb and ω-Zr + α-Zr phases, with a relative density of approximately 98%, using the Spark Plasma Sintering method and the ultra-high pressure method were obtained. X-ray diffraction methods were used to determine the content of individual zirconium phases in the materials. Stresses were measured in alpha and omega zirconium phases by the sin2 ψ diffraction method for all investigated materials. Hardness, tensile strength and elongation of materials were measured. The greatest elongation of 7.1% was found for sintered materials containing ω–Zr. The presence of the ω - Zr obtained under ultra-high pressure conditions does not significantly affect the stress level in ω Zr and in the α-Zr phase of the High Pressure – High Temperature sintered material. Tribological tests were carried out using the ball-on-disk method, with alumina as counter-samples. The research showed an adverse effect on the abrasive wear of the high-pressure omega Zr phase. The zirconium oxidation process and the separation of the oxide from the wear surface plays an important role in the abrasion of all sintered zirconium materials.