Influence of chromium content on the hydrogen storage and corrosion behavior of Mg-Ca-Si-V-Cr amorphous alloys

Abstract

To enhance the overall efficiency of Mg-based alloys, Mg-Ca-Si-V-Cr amorphous alloys with various Cr contents were prepared using the mechanical alloying method. The alloys were then characterized using X-ray diffractometer, energy dispersive X-ray fluorescence, scanning electron microscope, energy dispersive spectrometer, and electrochemical workstation to measure the mechanical property, hydrogen storage property, charge/discharge cycle stability, and corrosion resistance of the alloys. The results indicated that the Mg-Ca-Si-V-Cr magnesium-based alloys with varying Cr contents were amorphous in structure, featuring a uniform distribution of alloy particles on their surfaces. These alloys demonstrated outstanding overall performance. At a Cr content of 6 wt%, the synthesized Mg-Ca-Si-V-Cr alloy powder possessed the maximum peak load of 10.12 kN, indicating higher load-carrying capacity. The alloy achieved optimal hydrogen absorption performance, with a maximum H₂ absorption equal to 4.23 wt%. Its value dropped to 3.96 wt% after 10 min of hydrogen absorption, accounting for 94 % of the maximum absorption capacity. Moreover, the alloy displayed a distinct H₂ desorption plateau, providing a desorption pressure of approximately 0.5 MPa. The discharge capacity of the fabricated Mg-Ca-Si-V-Cr alloy initially increased from 475.67 to 495.88 mAh/g before gradually declining to 412.28 mAh/g during testing, achieving a maximum capacity retention rate of 86.78 %. At this time, magnesium-based alloy demonstrated a minimum corrosion current of 1.84 × 10⁻⁶ A/cm² and a maximum corrosion potential of −0.373 V. These results indicate that the Mg-Ca-Si-V-Cr alloy powder achieved its best overall performance at a Cr content of 6 wt%.