Journal de la métallurgie des poudres et des mines

Abstrait

Harmonic Structure Design and Mechanical Properties of Pure Ni Compact

Ota M, Shimojo K, Okada S, Vajpai SK and Ameyama K

Conventional material developments have emphasized ultrafine grain refinement and homogenization; however, “nano and homo” materials do not usually satisfy the need to be both strong and ductile, which are of course rather contradictory characteristics. On the other hand, "Harmonic Structure Materials Design" creates a "nano- and heterogeneous microstructure", and the harmonic structure materials can overcome that antinomy through its unique microstructure. The procedure to create the harmonic structure is accomplished by using one of the non-equilibrium powder metallurgy (PM) processes called the Severe Plastic Deformation (SPD) PM process. The harmonic structure materials consist of Ultra-Fine Grain (UFG) and coarse grain structures known as “shell” and “core”, respectively. They have a network structure of continuously connected shells, and simultaneously demonstrate both high strength and elongation, especially a large uniform elongation. In the present study, pure Ni powder is processed so as to produce the harmonic structure materials. The deformation mechanism is analyzed based on the strain hardening behavior.