COMBUSTION SYNTHESIS OF ZR-AL INTERMETALLIC COMPOUNDS

The combustion syntheses of all the intermetallic compounds in the Zr- Al binary system have been investigated. Analyses of the reaction prod ucts show that for compositions of the reacting mixture richer than 60 at.% in Al the products always contain a mixture of ZrAl3, ZrAl2 and Zr2Al3 in different proportions. Zr-rich samples always produce a mixt ure of Zr5Al3, Zr3Al2, ZrAl2 and Zr2Al3. DTA investigations have shown that the exothermic process responsible for the front propagation is represented, for all starting compositions, by the reaction of molten aluminum with solid zirconium to form ZrAl3. When fine powdered reacta nts are used, solid-state interaction also contributes to the reaction ignition.