Improvement of Powder Properties and Chemical Homogeneity of Partially Alloyed Iron Powder by a Nanopowder Process

Abstract

The present investigation focuses on the improvements in chemical homogeneity and related powder properties of partially alloyed Fe 1.50Cu1.75Ni0.50Mo powder by using a nanopowder process. The nanosized oxide powders of CuONiOMoO 3 were prepared by ballmilling for the alloying elements and blended with iron powders. The powder mixture was annealed in a reducing atmosphere, in order to reduce the oxide powders and thereafter partially alloyed with the iron powder. The produced powder was used to evaluate the microstructure, chemical composition, compressibility, and sinterability. It was found that the powder had a uniform distribution of alloying elements with high compositional homogeneity. The fine alloying elements were mostly located in the grooves of the iron powder surface, yielding morphological change, which effectively improved the flow, packing and compaction properties of the powder. The nanopowder process also promoted a diffusion reaction during sintering at 1200°C for 2 h with a homogeneous microstructure and chemical composition.

Thixotropic properties of multi-functional binder and compaction behaviour of the low alloyed binder-treated powder

“…The metallic additives of Cu, Ni, Mo, C or the other alloying elements are used to improve the mechanical properties of iron-based powder metallurgical products [3,4], while the addition of lubricant to the powder is effective to reduce the friction between mould wall and powder as well as the internal friction between powder particles during the compaction process [5][6][7][8]. However, the resulting powder mixtures are susceptible to segregation during mixing or handling due to the different particle size, morphology, and specific gravity of the powders [9][10][11][12]. The chemistry homogeneity of the powder mixture determines the die cavity filling performance, the morphology or size of the pores, and the resulting mechanical properties of the PM components.…”