Optimization of Cr/Mo molar ratio in FeCoCrMoCBY alloys for high corrosion resistance

The corrosion behavior of bulk metallic glasses(BMGs)(Fe41Co7Cr15Mo14C15B6Y2)100-xCrx(x=0,4,8,12,molar fraction,%)was investigated in1mol/L HCl aqueous solution with electrochemical tests.The electrochemical measurements demonstrate that the passive current density of Fe-based amorphous alloy is reduced by about one order of magnitude,and meanwhile,the stability of passive film can be guaranteed by the Cr/Mo molar ratio.The Mott–Schottky(M–S)curves show that the passive film is the densest when the molar ratio of Cr/Mo is between1.37and1.69.X-ray photoelectron spectroscopy(XPS)analysis was performed to clarify chemical states of elements in the passive films.The results show that the corrosion resistance of the alloy is related to the molar ratio of Cr/Mo.The stability of passive film is determined by the synergistic action of Cr and Mo elements.The main component of the passive film is Cr3+oxide.When the potential is greater than0.5V(vs SCE),Mo6+ions play an important role in keeping the stability of the passive film.The appropriate molar ratio of Cr/Mo can reduce the dissolution rate of the passive film.

Development of Ti-V-Cr-Mn-Mo-Ce high-entropy alloys for high-density hydrogen storage in water bath environments

The V-based body-centered cubic(BCC)-type hydrogen storage alloys have attracted significant attention due to their high theoretical hydrogen storage capacity of3.80 wt%.However,their practical application faces challenges related to low dehydriding capacity and poor activation performance.To overcome these challenges,a BCC-type Ti-V-Cr-Mn-Mo-Ce high-entropy alloy(HEA)with an effectively dehydriding capacity of 2.5 wt% above 0.1 MPa was prepared.By introduction of Mo and conducting heat treatment,the precipitation of Ti-rich phase in HEA was successfully suppressed,resulting in improved compositional uniformity and dehydriding capacity.Consequently,the effective dehydriding capacity increased significantly from 0.60 wt% to 2.50 wt% at 65℃,surpassing that of other types of hydrogen storage alloys under the same conditions.Moreover,the addition of 1 wt%Ce enabled initial hydrogen absorption at 25℃ without the need for activation at 400℃.Furthermore,Ce doping reduced the dehydriding activation energy of the Ti-V-Cr-Mn-Mo-Ce HEA from 52.71 to 42.82 kJ·mol^(-1)Additionally,the enthalpy value of dehydrogenation decreased from 46.89 to 17.96 k J·mol^(-1),attributed to a decrease in the hysteresis factor from 0.68 to 0.52.These findings provide valuable insights for optimizing the hydrogen storage property of HEA.