Studies on the Effect of Processing Parameters on Microstructure and Properties of Magnesium Compacts Prepared via Powde
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ORIGINAL ARTICLE
Studies on the Effect of Processing Parameters on Microstructure and Properties of Magnesium Compacts Prepared via Powder Metallurgy Prem Prakash Seth1 • Om Parkash1 • Devendra Kumar1
Received: 29 April 2020 / Accepted: 25 August 2020 Ó The Indian Institute of Metals - IIM 2020
Abstract The present study involves the investigation on the effect of processing parameters of powder metallurgy on the microstructure and hardness characteristics of the green as well as sintered specimens of magnesium. The processing parameters include the high-energy ball milling time, compaction pressure, and sintering temperature. From SEM images of 1, 3, and 5 h ball-milled powders, it is revealed that the sequence of change of morphology and size of particles is: flattening (formation of lamellas), fracturing (cracking of lamellas), and dynamic balance (adherence of a small particle with other particles and fracturing), respectively. The average particle size decreases with increasing ball milling time. 0, 1, 3, and 5 h ball-milled powders are compacted at different pressures. It is found that green density of the compacts of ball-milled powders depends on the morphology of powder particles, particle size, and compaction pressure. The selected samples were sintered at 500, 550, and 600 °C for 1 h. SEM characterization indicates that grain growth occurs with increasing sintering temperature. With constant mass, the sintering theory indicates that grain growth of larger particles takes place at the expense of smaller particles due to the difference of surface curvature. The density and hardness of sintered samples were calculated by using Archimedes principle and Vickers hardness tester, respectively.
& Devendra Kumar [email protected] 1
Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India
Keywords Magnesium Powder metallurgy Ball milling time Particles size Compaction pressure Green density Sintering temperature
1 Introduction Magnesium has gained widespread attention from the scientific community for advanced research to fulfill the present demands of lightweight structural materials of our society. Magnesium has the lowest density as a structural metal that has high stiffness-to-weight ratio [1]. One unit volume of magnesium is 35% and 78% lighter than aluminum and iron, respectively. Apart from low density, magnesium has a large number of advantageous properties, viz. high specific strength, the ability of turning and milling at high speed [2], good damping capacity and high-dimensional stability. Magnesium is easily recyclable [2]. For the use of magnesium as a structural material, it is necessary to overcome the limitations of magnesium. At ambient temperature, the ductility of magnesium is very low and is difficult to form because magnesium has a hexagonal closepacked crystal structure (HCP) [3, 4]. Due to heavy metal contamination, the corrosion resistance of magnesium is low [4]. Powder metallurgy (PM) process can be used
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