Fractography: Fracture Energy and Quantitative Metallographic Correlation for Tungsten-Silver Composite Materials

Tungsten-silver materials were made by two different powder metallurgical techniques which resulted in alloys having a wide latitude of structural variation in terms of volume fraction, particle size, and distribution. A correlation of G_Ic, the critical strain energy release rate, was made with the quantitative metallographic parameters ¯L_3Ag, the mean intercept length within the silver phase; C, the contiguity of the tungsten phase; and $VνAg$⁠, the volume fraction of the silver phase. A term composed of these three parameters was found to have a good correlation with G_Ic for all the alloys. A study of the fracture surfaces of each alloy by energy-dispersive X-ray analysis shows the silver content of the fracture surfaces decreases as the toughness of the alloys decreases.