Effect of Short Attritor-Milling of Magnesium Alloy Powder Prior to Spark Plasma Sintering.

Peter Minárik,Robert Král,Mária Zemková,Stanislav Šašek,Jan Dittrich,Jiří Kozlík,František Lukáč,Michal Knapek

doi:10.3390/ma13183973

Abstract

The spark plasma sintering (SPS) technique was employed to prepare compacts from (i) gas-atomized and (ii) attritor-milled AE42 magnesium powder. Short attritor-milling was used mainly to disrupt the MgO shell covering the powder particles and, in turn, to enhance consolidation during sintering. Compacts prepared by SPS from the milled powder featured finer microstructures than compacts consolidated from gas-atomized powder (i.e., without milling), regardless of the sintering temperatures in the range of 400–550 °C. Furthermore, the grain growth associated with the increase in the sintering temperature in these samples was less pronounced than in the samples prepared from gas-atomized particles. Consequently, the mechanical properties were significantly enhanced in the material made of milled powder. Apart from grain refinement, the improvements in mechanical performance were attributed to the synergic effect of the irregular shape of the milled particles and better consolidation due to effectively disrupted MgO shells, thus suppressing the crack formation and propagation during loading. These results suggest that relatively short milling of magnesium alloy powder can be effectively used to achieve superior mechanical properties during consolidation by SPS even at relatively low temperatures.

Highlights

The fast development of new sintering and additive manufacturing methods continuously increases application possibilities of powder metallurgy
A short attritor-milling of the gas-atomized AE42 magnesium powder was performed in order to fragment MgO shell usually present on the powder particles’ surface and, in turn, to improve consolidation during sintering
The study was primarily focused on the effect of short milling on the microstructure and mechanical properties of the sintered samples, and the main conclusions are as follows:

Summary

Introduction

The fast development of new sintering and additive manufacturing methods continuously increases application possibilities of powder metallurgy. The spark plasma sintering (SPS) technique is nowadays considered to be one of the most advanced sintering techniques This method, which involves high loads and well controllable high heating/cooling rates [1], is capable of retaining fine-grained microstructure because of short sintering times [2,3]. It can enhance densification in comparison with other techniques regardless of the thin oxide shell often present on the particles’ surface [4]. 3D net-like MgO phase distribution is usually present in consolidated samples along the former powder particles’ boundaries [7,8,9] It was Materials 2020, 13, 3973; doi:10.3390/ma13183973 www.mdpi.com/journal/materials

Methods

Results

Discussion

Conclusion