A HISTORY OF FINE-GRAINED HARDMETAL

An attempt has been made to follow the scientific and technological steps associated with the production of fine grained hardmetal. This task has not been easy because of the restrictions placed by commercial-and in some cases research organisations-in not publicising relevant information until long after the date of the initial work. Thus, placing data in an historical, chronological order has been somewhat difficult. However, it has been possible to establish that as far back as 1929, approximately 6 years after the first patent was granted, Krupp/Osram workers had identified the positive aspects of tungsten carbide grain refinement. By 1939 they had also discovered the beneficial effects of adding a small amount of vanadium and tantalum carbide. This effectively controlled discontinuous grain growth. What was considered 'fine' in one decade was considered not so fine in the next. Thus a grain size in the range 0.5-3.0 mu m was considered fine in the early years but now we have entered, in 1993, the era of the nano-crystalline material with a grain size of 20-50 nm. Have we now reached the end of the story? It is hoped that the chronological data given in this paper will be of interest to those engaged in the hardmetal industry, whether in the past or present.