Cu 45 Mn 25 Al 15 Fe 5 Cr 5 Ni 5 high entropy alloy was prepared using casting route. Detailed microstructural analysis revealed the formation of dendritic structure in the as-cast sample. The results showed that the dendrite (DR) regions are riched with Cu and Mn, while the inter-dendrite (ID) regions are riched with Cr and Fe. Metallographic investigation was conducted using optical microscope and scanning electron microscope as well. Determination of phase analysis was carried out using x-ray diffraction. Corrosion properties were studied via Auto LAB PGSTAT 302N, supplied with Nova software. The investigated alloy demonstrates superior corrosion resistance with average corrosion rate 0.056 mm year −1 .
T ITANIUM alloys have long been recognized as outstanding strong, light and corrosion resistant alloys. TC21 alloy has recently received considerable attention due to its high strength, toughness, damage-tolerance properties and low crack propagation rate. Similar to steels, titanium alloys have demonstrated their capacity to produce martensitic microstructure upon suitable heat treatment. Their martensite and its transformations upon subsequent heat treatment proved to be an important tool to obtain controllable properties. The martensite (start) characteristic temperature (M s) has received some attention as regards its dependence on composition. On the other hand, no similar attention was given to the dependence of the other important martensitic (finish) characteristic temperature (M f) on composition. In view of the foregoing, this work was thus planned to fulfill this lacking information via subzero hardening treatments of TC21 α/β alloy. Detailed analysis of the so obtained microstructures via optical and scanning microscopy, and x-ray diffraction data has led to a quantitative estimation of the M f temperature and its composition dependence. Additionally, the hardening effect of those subzero hardening treatments was studied via hardness and microhardness measurements. Significant findings were recorded which are expected to help reaching useful property levels such as strength, wear resistance and damagetolerance.
Magnesium (Mg) and its alloys are one of a novel kind of biodegradable metallic implants which attracted much fundamental research to develop its clinical application. Nevertheless, it has more restrictions in biomedical applications because it degrades too fast at the early stage after implantation, thus commonly leading to some problems such as early fast mechanical loss, hydric bubble aggregation, gap formation between the implants and the tissue. This work aims to study the effect of 0.5 wt% Sb addition on the microstructure, mechanical properties and degradation behavior of as cast Mg-4wt% Zn alloy. The evaluation process was conducted using optical and scanning electron microscopy, X-ray diffraction, tensile and compression tests, in addition to a corrosion study by immersing in simulated body fluid (SBF). Results showed that Sb refines the grain size of the base alloy and also enhances its mechanical properties and degradation rate as well. These were due to the formation of the secondary phase of Mg 3 Sb 2 . To get better degradation rate, the Mg-4wt% Zn and Mg-4wt% Zn-0.5wt% Sb alloys are coated with Ca-P using autocatalytic technique. The results demonstrated that the formed coat layer improves the degradation rate of samples under the condition of this study. The current study shows that Mg-4wt% Zn-0.5wt% Sb alloy has good mechanical properties and when it coated by Ca-P, it gave a better corrosion resistance that makes it ideal for biodegradable medical application.
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