Synthesis of Ultrafine Particles of Intermetallic Compounds by the Vapor-Phase Magnesium Reduction of Chloride Mixtures: Part 1.Titanium Aluminides

摘要

A new chemical synthesis process for thepreparation of intermetallic has been developed. It involves thevapor-phase reduction of mixtures of constituent metal chloridesby magnesium vapor to produce intermetallic compounds in theform of fine powder. The advantages of the process include (a)the use of inexpensive raw materials,(b) low reactiontemperatures , and (c) products in the form of fine particles. PartI describes the synthesis of titanium aluminide particles by thismethod, whereas Part II presents the synthesis of nickelaluminides particles. Although nickel aluminides can also beprepared by the hydrogen reduction of nickel chloride andaluminum chloride vapor mixtures, titanium alumindies cannotbe produced by hydrogen reduction because of unfavorablethermodynamics. The effect of AlCl3/TiCl3 partial pressure ratioon the formation of different titanium aluminides was studied. Atwo-phase mixture containing 80 mol pct of TiAl+20 mol pct ofTiAl3 formed at an AlCl3/TiCl3 ratio of 10. The amount of TiAl3was 94 pct. The product particles were very fine in the sizerange of 0.2 to 0.3 μm.