Structure-Properties Relationship of Sintered Hard Materials Analyzed Quantitatively by Using an Image Analyzer

Particle analysis of hard materials with complex phases, such as cemented carbides and Mo sub 2 FeB sub 2 base hard alloys, has been performed by using an image analyzer. A conventional algorithm of the image analysis has some difficulties in getting accurate measurements of the microstructural parameters, such as mean particle size, contiguity and aspect ratio of hard particles. To solve this problem, a new algorithm for grain boundary detection has been developed by using a backscattered electron image, which shows electron channeling contrast (ECC) depending on the crystal direction difference in the aggregated hard particles. By applying this method to the Mo sub 2 FeB sub 2 base hard alloys, it is quantitatively elucidated that the transverse rupture strength (TRS) drop at lower sintering temperature is due mainly to the coalescence of the hard particles.