Effect of Relative Density on Microstructure, Corrosion Resistance and Mechanical Performance of Porous Ti–20zr Alloys Fabricated by Powder Metallurgy

Abstract

The microstructure, corrosion resistance and mechanical properties of a binary Ti–20Zr (at. %) alloy with differing porosities were investigated. The alloys were produced following a standard powder metallurgy with sintering at 1200 °C for 4, 6, and 8 h. A space holder agent was used to obtain two ranges of relative density, i.e., 74.8–89.3% and 54.6–66.7%. Metallographic examinations were conducted by using optical microscopy and scanning electron microscopy. The confirmation of chemical composition was performed by energy dispersive spectrometry and elemental mapping analysis. Electron backscatter diffraction analysis was conducted to investigate microstructure morphology. Phase identifications were detected by X-ray diffraction. Uniaxial compressive tests were carried out and also potentiodynamic polarization was employed to understand the corrosion performances of the alloys. Experimental results showed that the pore size and pore connectivity were able to be controlled by the sintering time and a fixed amount of space holder agent. The phase constituents of the alloys were characterized as a mixture of predominant hcp α phase and some distorted hcp α′ phase. As foreseen, the ultimate compressive strength and elastic modulus of the alloys increased with increasing relative density. Results of corrosion resistance revealed adding space holder reduced the polarization resistance of Ti–20Zr (at. %) sintered for 6 h from 15.4 to 14.09 Ω. However, volume fraction of general porosity did not affect the microstructure of the alloys. In conclusion, the relative density of the alloys achieved in this study played a crucial role on the mechanical properties and corrosion properties. © King Fahd University of Petroleum & Minerals 2023.