Influence of solid-solution treatment on corrosion performance of cast AM50 magnesium alloy
It was investigated by quenching the AM50 magnesium alloy test samples in water after T4 treating (420 °C) for 24 h. Then both kinds of the test bars were immersed in 3.5 wt. % NaCl saturation Mg (OH) 2 aqueous solution for 0, 24 and 72 h. Then tensile tests were taken. The microstructure of the samples was analyzed by scanning electronic microscope and X-ray diffraction. The results show that though solid-solution treatment improved the corrosion residual strength of the cast AM50 magnesium alloy for 24h, the deeper corrosion pits developed on the heat-treatment samples on 72h caused more drop of the strength compare to the untreated samples. The solid-solution treatment and the extreme depth theoretical of corrosion pits effect together to the corrosion residual strength.
Effect of heat treatment on corrosion behaviour of magnesium alloy AZ91D in simulated body fluid
Abstract The research explored ways of improving corrosion behaviour of AZ91D magnesium alloy through heat treatment for degradable biocompatible implant application. Corrosion resistance of heat-treated samples is studied in simulated body fluid at 37 °C using immersion and electrochemical testing. Heat treatment significantly affected microgalvanic corrosion behaviour between cathodic β-Mg 17 Al 12 phase and anodic α-Mg matrix. In T4 microstructure, dissolution of the β-Mg 17 Al 12 phase decreased the cathode-to-anode area ratio, leading to accelerated corrosion of α-Mg matrix. Fine β-Mg 17 Al 12 precipitates in T6 microstructure facilitated intergranular corrosion and pitting, but the rate of corrosion was less than those of as-cast and T4 microstructures.
A Logistic Regression Model Explaining Recent State Casino Gaming Adoptions
The scholarly literature has argued that state fiscal stress, interstate tax competition, political feasibility, and economic development goals were the main reasons underlying the adoption of casino gaming by several American states. Archival data were collected and analyzed using logistic regression in an attempt to explain why some states have adopted casino gaming and others have not. Four statistically significant predictors of state casino gaming adoptions were discovered: moderate aggregate state ideological identifications, 1990 per capita tax rankings by state, longitudinal changes in state per capita taxes, and longitudinal changes in state job growth. These results suggest that motives related to political feasibility and economic development provide the best explanation of recent state casino gaming adoptions.