Simultaneous enhancement of hardness and corrosion resistance in liquid-metal-dealloyed Mg–Ti composites via short-time Al-melt treatment

Abstract

This study presents a short-time reactive Al-melt treatment that simultaneously enhances hardness and corrosion resistance in liquid-metal-dealloyed Mg–Ti composites. A three-dimensional bicontinuous Mg–Ti composite is first fabricated by immersing a Ti 30 Cu 70 precursor in a pure Mg melt, followed by immersion in a pure Al melt at 750 °C for 10 s. The initial Mg–Ti composite consists of a co-continuous α -Mg/ α -Ti matrix–matrix structure. After Al-melt treatment, the interconnected morphology is preserved, while the phase constitution is reconstructed into a multiphase α -Ti/TiAl 3 /Al 3 Mg 2 structure. TiAl 3 forms along the residual α -Ti ligaments, whereas the original Mg-rich regions transform into Al 3 Mg 2 . The average effective grain size of the residual α -Ti decreases from 3.7 to 0.8 µm, accompanied by increased local misorientation and a higher density of {11–22} compression twin boundaries. As a result, the surface hardness increases from 106 to 378 HV, while remaining above 260 HV at a depth of 260 µm. The Al-treated Mg–Ti composite also exhibits a markedly reduced corrosion rate in 3.5 wt.% NaCl solution, decreasing from 13.2 to 0.5 mm/year based on hydrogen evolution measurements and from 17.2 to 0.7 mm/year based on weight-loss measurements. Scanning Kelvin probe force microscopy reveals that the initial direct α -Mg/ α -Ti interface, with a Volta potential difference of approximately 635 mV, is replaced by α -Ti/TiAl 3 and TiAl 3 /Al 3 Mg 2 interfaces with lower potential differences of approximately 271 and 285 mV, respectively. Overall, the short-time Al-melt treatment enables simultaneous hardness increase and corrosion mitigation through rapid interfacial reconstruction and phase transformation while preserving the bicontinuous structure.

The authors' abstract, as published at the source. Journal of Magnesium and Alloys, 2026 · DOI ↗