Physical Basis of Nondestructive Evaluation on Microstructure Parameters in Cemented Carbides WC-Co

The consistent numerical value relationship regularity between the true γ-phase mean free path λ and the nominal γ-phase mean free path λγ was deduced by means of both calculating physical property measured data with the γ-phase magnetism analysis and measuring directly γ-phase mean free path with stereo-metallographic technique. The respective relationships of the γ-phase mean free path λ or the WC-grain contiguity CWC with the elemental parameters γ-phase volume fraction fγ and WC mean grain size LWC were deduced from the relation between λ and λγ. The physical basis evaluating nondestructively microstructure parameters in cemented carbides WC-Co by use of to replace stereo-metallographic test by physical property measurement was expounded. The results showed that the microstructure feature of two-phase WC-Co alloy could determined by the two basic parameters fγ and LWC;fγ and LWC were respectively determined by cobalt content and WC mean partical size in raw material and were restricted by γ-phase composition under sintering;the LWC growth degree bore a positive-going relation to sintering time, but the fγ value bore no relation to sintering time;the fγ increment and the LWC growth degree bore opposite-going and positive-going relation to the carbon content increment in alloy respectively, so the fγ increment was helpless to the WC grain size growth by recrystallization under sintering.