Solidification Behavior of Commercial Magnesium Alloys

Abstract

In this thesis, the solidification behavior of AZ91D, AM60B and AE44 commercial magnesium alloys has been studied experimentally by differential scanning calorimeter (DSC) and optical microscopy. The effect of different cooling rates on the transition temperatures and microstructures were analyzed. It was found that the effect of cooling rate on the solidus temperature is more significant than on the liquidus. The solidus temperature decreases clearly with increasing cooling rates, but for the liquidus temperature there is slightly increasing trend.The latent heat of solidification was also calculated and found that it increases when the cooling rate increases. Thermodynamic calculations were made using FactSage along with VLGM database and were compared with the experimental findings as well as with the literature data.Thermodynamic calculations were also utilized to understand the microstructures as well as the phase distribution. The microstructural details of as-cast and post-DSC samples have also been investigated using optical microscope. Finally, a relationship between cooling rate and transition temperature and solidification enthalpy has been established based on the general power law. Using this relationship it is possible to predict the transition temperatures and solidification enthalpies of these alloys at high cooling rates.

Microstructural and Mechanical Characterization of AM60B Alloy Cast by RSF Process

“…the solid fraction formed by RSF at 613 °C, was estimated by optical microscopy to be ~36%: this result is in accordance with Ref. [6]. In every step, the microstructure was finer close to the casting surface than in the centre of the casting.…”

The effect of cooling rate on thermophysical properties of magnesium alloys

“…Thermal analysis technique is a useful tool to obtain the value of phase-transformation temperature and heat of solidification of multicomponent alloys. Many researchers [1][2][3][4][5][6][7][8][9][10][11][12][13] studied the solidification behavior of magnesium alloys, but the effect of cooling rate on phase-transformation temperatures and enthalpy of solidification has not been investigated extensively in the literature. Hence, this work has been initiated to investigate experimentally the effect of cooling rate on phase-transformation temperatures and heat of solidification of the AZ91D, AM60B, and AE44 magnesium alloys using differential scanning calorimetry (DSC).…”

Influence of Cooling Rate on Microsegregation Behavior of Magnesium Alloys

“…It is to be noted that for the same alloy AM60, Wei and Warren [21] and Barbagallo et al [19] reported different amount of Al content in the grain boundary region, and this is due to the fact that the casting conditions of the samples were different. Han et al [22] reported that for permanent mold casting of AZ91D alloy in the dendritic center the aluminum concentration is 2.6 wt.%, but it is 11.7 wt.% at the dendrite edge, about 4.5 times higher than that in the dendrite center. Zhang et al [23] conducted experiments to compare the amount of microsegregation in permanent mold cast and die-cast AZ91 alloys.…”