A new method is described for dispersion hardening tungsten to improve its creep strength at high temperatures and thus make it more suitable for use in nuclear reac¬tors for space applications. Called the covapor deposition technique, this method in¬volves mixing vapors of WC1x and HfClx and reducing them with NH3 and H02 to produce a deposit of W interspersed with fine particles of HfN for strengthening. A by-product of the development of the covapor deposition technique is the discovery that finer grained vapor deposits of W can be achieved by partially nitriding the W to W2N during deposition and later removing the W2N by heat treatment above its 900℃ decomposition temperature.
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