EPMA STATE ANALYSIS OF FORMATION OF TIC D URING MECHANICAL ALLOYING OF MG, TI AND GRAPHITE POWDER MIXTURE

To prepare a TiC-dispersed magnesium, the mixtures of elemental Mg, Ti and graphite powder were mechanically alloyed up to 288 ks in Ar. The obtained fine grain mixture of the Mg-Ti-C system was heat-treated up to 773 K for 3.6 ks in vacuum. C K alpha X-ray spectra of TiC, graphi te, micro crystalline graphite and mechanically alloyed products were measured by an electron-probe microanalyzer (EPMA) with the second-ord er reflection of a Johann-type lead stearate multilayer pseudocrystal. The progress of the mechanical alloying (MA) reaction was monitored w ith the C K alpha X-ray spectral change which quantitatively reflects the amount of TiC in the reaction mixtures. The early stage of the MA reaction is solely a refinement of graphite; graphite did not react on Ti. The next stage is the formation of TiC from refined graphite and Ti. Heat-treatment accelerates the formation of TiC, but graphite is n ot completely converted into TiC with the MA reaction and heat-treatme nt because a small amount of refined graphite has been subsequently de tected in the reaction mixtures even after a prolonged MA time and hea t-treatment at 773 K.