Role of micro-Ca/In alloying in tailoring the microstructural characteristics and discharge performance of dilute Mg-Bi-Sn-based alloys as anodes for Mg-air batteries

The influence of micro-Ca/In alloying on the microstructural charac teristics,electrochemical behaviors and discharge properties of extruded dilute Mg-0.5Bi-0.5Sn-based(wt.%)alloys as anodes for Mg-air batteries are evaluated.The grain size and texture intensity of the Mg-Bi-Sn-based alloys are significantly decreased after the Ca/In alloying,particularly for the In-containing alloy.Note that,in addition to nanoscale Mg_(3)Bi_(2)phase,a new microscale Mg_(2)Bi_(2)Ca phase forms in the Ca-containing alloy.The electrochemical test results demonstrate that Ca/In micro-alloying can enhance the electrochemical activity.Using In to alloy the Mg-Bi-Sn-based alloy is effective in restricting the cathodic hydrogen evolution(CHE)kinetics,leading to a low self-corrosion rate,while severe CHE occurred after Ca alloying.The micro-alloying of Ca/In to Mg-Bi-Sn-based alloy strongly deteriorates the compactness of discharge products film and mitigates the"chunk effect"(CE),hence the cell voltage,anodic efficiency as well as discharge capacity are greatly improved.The In-containing alloy exhibits outstanding discharge performance under the combined effect of the modified microstructure and discharge products,thus making it a potential anode material for primary Mg-air battery.

Effects ofslip mode on microstructure evolution and compressive flow behavior of extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy

The influence of the slip mode on the microstructure evolution and compressive flow behavior at different strains in an extruded dilute Mg−0.5Bi−0.5Sn−0.5Mn alloy was analyzed through electron backscatter diffraction,X-ray diffraction,transmission electron microscopy,and hot compression tests.The results showed that at a low strain of 0.05,the basal<a>,pyramidal<a>and<c+a>slip modes were simultaneously activated.Nevertheless,at the middle stage of deformation(strain of 0.1,0.2 and 0.5),the<a>slip mode was difficult to be activated and<c+a>slip mode became dominant.The deformation process between strains of 0.2 and 0.5 was primarily characterized by the softening effect resulting from the simultaneous occurrence of continuous dynamic recrystallization and discontinuous dynamic recrystallization.Ultimately,at strain of 0.8,a dynamic equilibrium was established,with the flow stress remaining constant due to the interplay between the dynamic softening brought about by discontinuous dynamic recrystallization and the work-hardening effect induced by the activation of the basal<a>slip mode.

Tailoring the microstructure and improving the discharge properties of dilute Mg-Sn-Mn-Ca alloy as anode for Mg-air battery through homogenization prior to extrusion

Mg-0.5Sn-0.5Mn-0.5Ca(wt.%) alloys with different microstructures are designed through casting and extrusion with and without homogenization treatment prior to extrusion(HPE).The influence of HPE treatment on the microstructural characteristics and resultant discharge properties of Mg-Sn-Mn-Ca alloy in extruded condition as anode for Mg-air battery was investigated.HPE treatment exerts a prominent effect on the grain structure and orientation,distribution of the second phase particles as well as the dislocation density of the extruded alloy.The HPE alloy exhibits a distinctly high cell voltage together with specific energy compared with that of Non-HPE one.Intermittent discharge tests confirm that the HPE alloy possesses a more excellent discharge activity and more stable discharge process than the NonHPE one.All results demonstrate that the HPE alloy is an attractive anode material for Mg-air battery with long-term storage and under intermittent discharge.

Microstructure,fracture behavior,in vitro corrosion resistance,and cytotoxicity of Zn-Mg/Mg-Zn-HAp laminated composites produced by spark plasma sintering

Ideal biodegradable materials exhibit suitable degradation rates and sufficient mechanical properties for their specific application.With these parameters in mind,Zn-Mg/Mg-Zn-hydroxyapatite(HAp) laminated composites were designed and fabricated by spark plasma sintering.This paper describes the structure,mechanical properties,in vitro corrosion resistance,and cytotoxicity of the Zn-Mg/Mg-Zn-HAp laminated composites.The compressive strength and elastic moduli of the laminated composites matched that of cortical bone and could effectively reduce the stress shielding effect as an implant with good biomechanical compatibility.Analysis of the fracture path and morphology after fracture toughness tests indicated that the Zn-Mg/Mg-Zn-HAp laminated composites exhibited significant capacity to prevent crack propagation,improving the fracture toughness.In vitro degradation experiments showed that the design of the laminated structure can provide a gradient degradation rate for the material.Furthermore,the laminated composites exhibited excellent biocompatibility and are promising candidates for orthopedic implants.