This study demonstrates the stabilization of Mg-3Ca foams by ex-situ addition of TiB2 particles (D50 = 8.045 mu m) as effective agents to enhance foam morphology and stability. TiB2 additions (3 and 5 vol%) delayed cell coarsening and preserved higher circularity by increasing melt viscosity. While Mg-3Ca foams contracted during prolonged foaming (5-15 min), TiB2-containing foams retained and even enhanced their expansion, achieving volumes of 625 % and 652 % compared to 566 % for the base alloy. A single-film stabilization model revealed thicker and smoother films (130 mu m to 323 mu m) with reduced oxide accumulation in the presence of TiB2 particles, highlighting their role in enhancing foam longevity. Quasi-static compression tests indicated that higher TiB2 content introduced serrated deformation, slightly reducing energy absorption. These findings advance our understanding of particle-stabilized Mg foams, offering new opportunities for lightweight, high-performance materials

The present study aims at investigating the effect of pre-milling nickel (Ni) and aluminium (Al) powders on the sintering behaviour of NiAlFeCoCr high entropy alloys (HEA). As-milled NiAlFeCoCr HEA was prepared by mixing the Ni, Al, Fe, Co and Cr powders (in equiatomic ratio) for 10 h in a planetary ball mill. In case of pre-milled (NiAl)FeCoCr HEA, Ni and Al powders were initially milled for 5 h and this mixture was then further milled with Fe, Co and Cr powders for another 10 h. XRD, SEM -EDS, TG-DSC and Dilatometric analysis were performed for the characterization of these HEAs. The formation of FCC and BCC phases was observed in both, as-milled and pre-milled HEAs. The sintering behaviour (at 1000-1200 degrees C) of the HEAs was compared and observed that as-milled HEA sintered by viscous flow mechanism, which was absent in case of pre-milled HEA. An exothermic reaction observed in the as-milled HEA at 518 degrees C representing Ni and Al reaction, was absent in the pre-milled HEA, indicating that Ni and Al had reacted during the premilling process. The micro-Vickers hardness of as-milled HEA also increased from 638 +/- 8.73 HV to 662 +/- 12.24 HV upon pre-milling. (c) 2024 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Mg-3Ca alloys with varying Zn concentration (0 to 5 wt pct) were foamed using CaCO3 via liquid processing route and their compressive and energy absorption behavior were investigated. The Mg-Zn-Ca alloy foams revealed a uniform cell structure with minimum defects and improved expansion in comparison to Mg-3Ca foams without zinc. The cell wall microstructure of Mg-3Ca alloy foam revealed micro-cracks and MgO particle agglomerates at the gas-solid interfaces. Upon Zn addition, the micro-cracks were diminished to larger extent and finely MgO particles were dispersed homogenously at the gas-solid interface. Pore diameter of the foams decreased from 2.29 to 2.06 mm, while circularity improved from 0.60 to 0.72 with increasing Zn content from 0 to 5 wt pct. The peak compressive stress also improved from 1.64 to 5.09 MPa with 5 wt pct Zn addition to Mg-3Ca foam. The ductility number improved from 0.66 to 0.75 while retaining energy absorption efficiency 60 pct in the plateau region. The improved mechanical properties of Mg-Zn-Ca foams are due to elimination of brittle Mg2Ca and increase in the Mg6Zn3Ca2. The reduced pore diameter, circular and equiaxed pores and crack-free interfaces in the foams were also contributed to the better mechanical properties.

Pure Mg foams stabilized by ex-situ added CaO particles were developed in this study. Mg/xCaO foams (x = 5, 7 and 10 wt.

This study aims at using Fly Ash (FA) particles as reinforcement particles in the Mg matrix and studying the thermal properties of the novel Mg-3Ca/FA composites produced via liquid processing route. About 3, 6 and 9 wt.

The present paper investigates the stabilization of Mg-3Ca alloy and Mg-3Ca/SiC/5p composite foams with and without the addition of 0.12 wt.% beryllium. In Mg-3Ca alloy foam, Be addition has shown a significant improvement in the expansion and pore structure. Whereas, in case of Mg-3Ca/SiC/5p composite foams, the SiC particles stabilized the foam effectively, while Be addition does not show any distinguishable improvement in the foam structure. The formation of BeO and the dense coverage of SiC particles in the gas–solid interface of Mg-3Ca and Mg-3Ca/SiC/5p composite foams, respectively, are the reasons for the foam stabilization. Mg-3Ca/SiC/5p composite foam exhibited lowest foam density of 0.10 g/cm3. The quasi-static compression test shows that Mg-3Ca-0.12Be/SiC/5p composite foam containing Be exhibited lower foam density and higher normalized compressive strength. The energy absorption capacity per unit foam density in Be containing foams was also higher.

The present work is the first ever study where the influence of beryllium (Be) addition on the stability of Mg alloy foam was investigated. Mg-3Ca alloy foams were produced by the liquid processing route with and without Be micro-addition. CaCO 3 was used as a blowing agent. Mg-3Ca alloy foam without Be resulted in stable foam but exhibited low expansion with poor foam structure. Be addition significantly increased foam expansion and improved their structure. The expansion and the structure of the Mg foams obtained are comparable with that of commercially available aluminum foams. The XPS analysis confirmed the presence of BeO at the gas-solid interface of Mg foam. Be stabilizes the gas-solid interface of the foam by forming a smooth and crack-free surface of BeO layer which prevents the continuous oxidation of liquid foam and also minimizes the loss of blowing gas thereby enhancing the stability of Mg-3Ca alloy foams.

The present work reports on foaming of magnesium alloys and composites using MgCO3 as the blowing agent. Foaming was done via the molten metal route by direct addition of MgCO3 in molten Mg. The alloys and composites required for foaming were prepared by varying the concentration of aluminum (10 to 30 wt pct) and calcium (0 and 2 wt pct) in Mg. SiC of 10-µm size and about 10 to 20 vol pct was added as reinforcement particles in the composite. The liquidus temperature of the alloys and composites, the decomposition behavior of MgCO3, and the intrinsic oxides that formed in the melt have a significant effect on the structure of the foams. Mg alloys and composites with 30 wt pct Al showed better foaming behavior with higher expansion, lower density, good cell structure, and uniform cell size distribution due to the smaller difference between their liquidus temperature and the decomposition temperature of MgCO3. The addition of 2 wt pct Ca showed a significant effect on foaming, and the MgO and MgAl2O4 (spinel) particles formed in situ in the molten Mg during foaming acted as the stabilizing agents.

The present research work emphasizes on the study of micro-structure, corrosion and biological behaviour of novel Mg-(0-5)Zn-1Ca/(0-3)hydroxyapatite (HA) composites for future use as biomedical implantation. Microstructures showed a significant grain refinement with increasing Zn content along with HA agglomerates on the surface. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that Zn addition in Mg-1Ca alloy is assisting in inhibiting cathodic corrosion while HA addition in Mg-(0-5)Zn-1Ca alloy is increasing anodic corrosion along with Zn. Further, cytotoxicity analysis using direct and indirect contact methods were performed using L-929 cells, which showed that Zn addition (0–3 wt%) slightly increases cell viability and non-toxicity in Mg-1Ca alloy whereas a considerable improvement is observed after HA addition in Mg-Zn-1Ca alloys. Mg-1Zn-1Ca/3HA and Mg-3Zn-1Ca/3HA alloys/composites were observed to have controlled corrosion and non-toxic to L-929 cells.