72159544
Dec 20, 1962
Mar 10, 1964
REFRACTORY HARD METALS BEING COMPOUNDS FORMED BY REACTING BORON, CARBON, NITROGEN OR SILICON WITH EACH OTHER OR WITH TRANSITION METALS, SUCH AS TITANIUM, VANADIUM, CHROMIUM, ZIRCONIUM, COLUMMBIUM, MOLYBDENUM, HAFNUM, TANTALUM, AND TUNGSTEN
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