Creep in Powder Metallurgy Products

Abstract

Creep in Powder Metallurgy Products 211 moving extended distances in the lattice. This requires 1) generation of dislocations from discontinuities in the crystal lattice called dislocation sources. These may be segments of dislocations which are pinned at their ends, generally called Frank-Reed sources or grain-boundaries or free surfaces. 2) movement of the dislocations in the crystal lattice What happens when we apply a stress to the crystal? Under its influence dislocations are generated from the dislocation sources in the crystal. In single phase material this stress which causes generation of dislocation from sources is the stress associated with yielding.

Sintering Kinetics Across Pore Closure Transition Accounting for Continuous Increase in Grain Coordination with Density

“…7 The curve bounding the shaded domain represents the coordination of spheres in simple contact according to relation (2). The three full curves are potential sintering trajectories according to relations (3)(4)(5). one.…”

“…Sintering theory commonly distinguishes three stages: the initial stage during which the driving force is dominated by interface curvature gradients, the intermediate stage during which porosity consists of a fully open network of channels with quasiuniform interface curvature, and the final stage during which pores are closed pockets disconnected from one another [1][2][3][4] At equilibrium, pore closure cannot occur if w ≤ 60: triple lines then always remain wetted by a channel of pore. We will denote q pc the critical value of q at which pore closure occurs when w > 60.…”

Effect of heat treatment on microstructure and mechanical properties of hot-hydrostatically extruded 93W–4.9Ni–2.1Fe alloy

“…WHAs offer a unique combination of properties such as high density (16-18 g/cm À3 ), high strength (UTS1000-1700 MPa), high ductility (elongation 10-30%), good corrosion resistance and easy machinability. One of the strategic applications for these alloys is in ordnance, such as kinetic-energy (KE) penetrators [1][2][3].…”

Fabrication of porous aluminum with deep pores by using Al–In monotectic solidification and electrochemical etching

“…These include large surface area with respect to their volume, permeation of fluids, ability to hold fluids in their pores, and high strength to weight ratio. Powder metallurgy techniques [1][2][3] and a casting technique [4] produce isotropic porous media. The lotus-type porous media have also been produced through the metal -gas reaction during the solidification [5 -7].…”