1. Field of the Invention
This invention relates to carbonyl iron powder (CIP) premix compositions for metal injection molding (MIM), and more particularly, to improved premix compositions, and to a process for making such premix compositions which are characterized by predetermined particle sizes, and narrow particle distributions, of the respective powders therein, and which can provide sintered products having an enhanced sintered density, low porosity values and minimum alloy segregation.
2. Description of the Prior Art
CIP has been used for MIM of steel and other alloy parts since the inception of MIM technology. CIP material is advantageous for MIM processing because of its uniform, spherically-shaped, fine particles, and its highly reactive surface which provides an effective sintering reactivity. Accordingly, CIP has been a material of choice for most iron-based alloy articles made by the MIM process. However, these procedures are limited in scope at present because of the disadvantageous effect of alloy segregation, and the low sintered density and/or high porosity of the products obtained.
Accordingly, it is desired to provide new and improved CIP premix compositions, and a process for making such compositions, from which molded CIP-containing alloy products can be made commercially having advantageous physical properties including maximized sintered density, low porosity and enhanced sintered alloy uniformity.