Study of isothermical sintering of finely divided and mechanically alloyed iron powders

Abstract

The sintering kinetics has been studied and the sintering activation energies of finely divided iron powders and mechanically alloyed mixture of "iron – 0,5 % C – 5,6 % ferrophosphorus" have been calculated. Dislocation density calculated by the X-ray phase analysis and microscopic metallog- raphy increases up to 1011 cm–2; and the dislocation ordering process in the finely divided iron powders and mechanically alloyed mixture is found when milling time increases. Based on the porosity values, which vary in time of isothermal sintering at 900–1100 °C of powders finely divided for different times, Ivensen equation coefficients, sintering activation energy, and structural defect concentration being in evidence in the beginning of isothermal sintering are calculated. The results show the formation of dislocation structure with high density of thermally unstable dislocations to activate sintering slightly in the course of milling; the structural defects created in forming the solid solution during mechanical alloying and hetero- diffusion affect the sintering activation much more.