In this research, effect of minor alloying element Ca on microstructure, mechanical and biocorrosion properties of as-cast Mg-3Zn-0.3Zr-xCa (x = 0, 0.3, 0.6, 0.9) alloys were investigated for biomedical application. The result showed that Ca played a dual role in mechanical properties and corrosion resistance. With minor Ca addition, the microstructure of the alloy is significantly refined and more uniform. The elongation, tensile strength and corrosion resistance of the studied alloys increases and then decreases with the increase of Ca content. With increasing the Ca content to 0.6 wt-%, the new strip phase of Ca 2 Mg 6 Zn 3 can be found, and gives the best strength and corrosion resistance. It was thought that the alteration of the second phase and the microstructure affect the mechanical and bio-corrosion properties.
A series of novel red-emitting phosphors BaZrGe3O9 : Mn4+ (BZG : Mn4+) were synthesized through high-temperature solid-state reaction method in order to explore their capabilities for application as red-emitting phosphors. The phosphors were characterized by X-ray diffraction, photoluminescence spectra, and decay curve measurements at the temperature ranging from 80 to 500 K. The luminescence intensity increases to maximum at doping concentration of 0.2 mol.%, and then decreases with concentration. Serious thermal quenching was also revealed. Keywords: red-emitting phosphor, germanate, Mn4+, concentration quenching, thermal stability.
Biodegradable magnesium alloys have been extensively investigated for medical applications. In order to explore magnesiumg alloys with good degradable resistance, the effects of minor amounts of calcium and manganese elements on the corrosion behaviors of newly designed as‐cast degradable Mg‐4Zn‐xMn‐xCa alloys have been investigated systematically in this study. The microstructural evolution of various magnesium alloys are measured by optical microscopy, x‐ray diffraction, and scanning electronic microscopy. The corrosion properties are studied through immersion tests and electrochemical measurements. The results show that the grains are refined and the distribution of the intermetallic Mg‐4Zn‐xMn‐xCa alloys is rearranged by adding calcium and manganese elements. The lowest corrosion rate of 3.79 mm/y is achieved on the as‐cast Mg‐4Zn alloy with 0.2 wt.% calcium and 1 wt.% manganese addition. Besides, the corrosion potential (Ecorr) shifted to −1.546 VSCE with the addition of 0.2 wt.% calcium and 1 wt.% manganese. This is because the grain size refinement and the formation of Mg2Ca and Ca2Mg6Zn3 phases. The as‐cast Mg‐4Zn‐1Mn‐0.2Ca alloy can be considered an ideal material for biodegradable implant material application.
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