Abstract
A new master sintering curve (MSC) is proposed for Al-Mg alloy in order to effectively design the pressure-assisted sintering process. In this work, hot pressing experiments of Al-Mg alloy powders are performed. The changes of relative density during hot pressing are measured for the various heating rates of 5°C/min, 10°C/min, and 20°C/min at the fixed pressure of 50 MPa. A work of sintering, designated as Θ, is introduced and defined as Θ(t,T)=∫0t1/Texp-Q/RTdt. A work of sintering, Θ, could be interpreted as a measure for the amount of sintering work. The MSC in this work defines the relation between the apparent density and a work of sintering, Θ. Since the measurement of an apparent activation energy, Q, is very difficult, the correct value of Q is obtained numerically using a mean residual square method. Then, the master sintering curves for sintering of Al-Mg alloy powders are proposed for the sintering temperatures of 400°C and 500°C through scaling procedures. It is expected that the master sintering curves proposed in this work could help an engineer to design pressure-assisted sintering process for Al-Mg alloy.
Highlights
The demand for more light weight, fuel efficient, and enhanced performance automobiles has stimulated research and development in high-strength and high formability aluminum alloys
This study is concerned with the development of master sintering curves for Al-Mg alloy, which can provide a useful method to quantify the densification behavior during sintering
Hot pressing of Al-Mg alloy powders is performed under the constant heating rate at 5, 10, and 20∘C/min for two schedules: (1st schedule) peak temperature 400∘C and holding time 30 min; (2nd schedule) peak temperature 500∘C and no holding time
Summary
The demand for more light weight, fuel efficient, and enhanced performance automobiles has stimulated research and development in high-strength and high formability aluminum alloys. If the densification during sintering could be predicted from the sintering data that are really available, it would be helpful for engineers to design a new sintering process. The master sintering curve enables engineers to predict the densification behavior under arbitrary time-temperature schedules with the help of a minimum of preliminary experiments. This curve has been known as sensitive to the factors such as starting morphology of the powder, fabrication route, dominant diffusion mechanism, and heating condition used for sintering [6]. The motivation for the present study is to extend the concept of the master sintering curve into the realm of hot pressing with metallic powders and to establish the pressure-assisted master sintering curve of Al-Mg alloy
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