Mean Grain Size and Pore Effects on Ultrasonic Properties of WC-Fe-Ni and SiC-Fe-Ni Composites

In this work, electroless nickel plating technique was used with WC-Fe and SiC-Fe powders. Plated powders were sintered at temperature ranging from 600 degrees C to 1100 degrees C under argon shroud in Phoenix microwave furnace. The mean grain size is determined by using three different techniques namely ultrasonic velocity, ultrasonic attenuation, and rate of screen heights of successive peaks according to the pulse-echo method by using a 2 MHz and a 4 MHz probes compared with the scanning electron microscopy images. In addition, the relative effects of porosity on ultrasonic attenuation and velocity in the WC-Fe-Ni and SiC-Fe-Ni composite samples are studied. It is seen that the ultrasonic velocity, the ultrasonic attenuation, the rate of screen heights of successive peaks have a linear relation with the mean grain size of samples. However, the correlation coefficients of porosity graphs have higher values than mean grain size graphs for the composite materials as expected. This indicates that porosity determines the ultrasonic velocity and attenuation for the composite samples.