An overview of dynamic compaction in powder metallurgy

Abstract

This paper is a critical review of dynamic compaction as a means to densify metal powders. Dynamic compaction was discovered in the 1960s. Most of the investigations since then have focused mainly on the physics dealing with energy, motion and force aspects of the process. Owing to this, there is a lack of knowledge of the effects of preprocessing and processing factors on this process. This knowledge gap has created skepticism in the PM community about this process' practice. This review attempts to bridge this gap and highlights the powder metallurgical aspects of dynamic compaction by emphasising the key powder related factors and processing parameters affecting dynamic compaction. Powder related factors include powder characteristics and the processing parameters including the machine operating parameters. Attention has been given to iron, aluminium and copper powders. Through this review, this article paves the way to design of high density dynamic compaction systems based on the final PM component requirements, by adjusting the material and processing parameters.

Shock compression of reactive powder mixtures

“…25,64 The particular micromechanical modes active within these regions will vary according to the strain-rate and powder configuration, once again defined by the particle size, morphology, orientation, distribution, and initial density. The recent review by Sethi et al 70 provides an in-depth discussion of the dynamic consolidation of single-component powders. For multi-component powder mixtures, the added heterogeneity of dissimilar yield strengths, mass densities, and sound speeds will also play an important role in how shock energy dissipation is partitioned and localised.…”

A Control Method of High Impact Energy and Cosimulation in Powder High‐Velocity Compaction

“…Furthermore, energy control is a significant aspect of HVC technology. Sethi et al [5] believed that once the critical limit of the speed of sound is reached, energy, not velocity, is the critical parameter that controls the shock wave phenomenon for easily compressible materials. At higher energy levels, the velocity has even minor negative effect on the densification.…”

“…Compared with conventional compaction (CC), HVC improves the green density of metal powders and enhances the uniformity of the density distribution [5].…”

“…Zhang et al [2] enhanced the green density (0.11-0.25 g/cm 3 ) using the annealed powder in iron-based alloy HVC. Zhang et al [8] utilized warm die HVC to enhance the green density of an iron-based alloy (0.09-0.27 g/cm properties of the metal powder product can be enhanced [2,5,8]. Shoaib and Kari [11] simulated nonlinear elastoplastic shock waves in particle systems subjected to HVC using the discrete element method.…”

“…Sethi et al [5] listed four types of dynamic compaction equipment of various configurations, namely, guns, rams, electrical impulse, and explosive units, used to produce high impact energy and the corresponding operating parameters. Vivek et al [3] used a variation of electrically driven vaporizing foil actuators for the dynamic compaction of Ti-based alloy powders.…”