Evolution of microstructure, mechanical properties and corrosion behaviors using cooling rate regulation in a novel ZrTi-based alloy

Abstract

For the development of biological ZrTi alloys with excellent properties, microstructure evolution, mechanical properties and corrosion behaviors of a novel Zr–40Ti–4.5Al–4.5 V (Z40T, wt.%) alloy resulted from different cooling rates have been investigated. Variations in the phase composition and microstructure are observed with X-ray diffraction, metallography, scanning and transmission electron microscopy analyses. The results demonstrate that α'' martensite can be formed through a nondiffusive phase transformation of the β phase during rapid cooling. However, slow cooling rates provide a stable α phase due to atomic diffusion and rearrangement. Furthermore, the grain size of each phase also changes as a result of different cooling rates. Moreover, the mechanical properties and corrosion behaviors are determined with uniaxial tensile testing and potentiodynamic polarization testing in NaCl solution. The mechanical properties and corrosion behaviors of the Z40T alloy are closely related to the phase composition and microstructure. The sample strength and fracture elongation changes obviously as the cooling rates change from water cooling to slow cooling. Analysis of potentiodynamic potential curves indicates that corrosion potential increases and corrosion current density decreases as the cooling rate is increased from slow cooling to water cooling. The variation in the mechanical properties and corrosion behaviors of the Z40T alloy are ascribed to the differences in the crystal structure and grain size of the constituent phase.

Keywords

• ZrTiAlV alloy
• Cooling rates
• Microstructure
• Mechanical properties
• Corrosion behaviors