The true microstructure of solid materials - Materialographic specimen preparation - from Sorby to the present

The microstructure of a material can yield information regarding many of it s properties. For this reason materialographic - or if the older and more u ser friendly term metallographic is to be used preparation is extremely imp ortant in both production as well as in research. In 1863 H. C. Sorby revealed the first "true microstructure" of steel, the importance of the preparation of which was however ignored for many years w ith the result that the microstructures observed continued to be riddled wi th numerous artifacts. In the thirties, the American J. R. Vilella again to ok up the theme of preparation in revealing the "true structure" of metals, whilst in the fifties to the sixties the Australian L. E. Samuels convinci ngly described how to prepare metals by mechanical means in order to reveal their true structures. In revealing the true structure of a material, or one containing a minimal number of artifacts, by mechanical preparation, the removal rate and the am ount of surface deformation introduced are the two most important factors. Prior to the Second World War such preparations were carried out manually u sing Al2O3 (abrasive paper and alumina). In the fifties, semiautomatic mach ines with rotating discs were developed with SiC and diamond being used as the abrasives. The preparation of a specimen can actually introduce artifacts into the mat erial causing a "false" microstructure to appear which can mistakenly be ac cepted as the "true" microstructure of the material.