THE INFLUENCE OF PROCESS CONTROL AGENT (P.C.A)’S STATE ON EXPEDITION OF MECHANICAL ALLOYING OF NANOSTRUCTURE TIAL(γ) ALLOY

Abstract In this research, the effect of two process control agent: methanol (liquid state) and stearic acid (solid state) on mechanical alloying process of Ti and Al with equal at%(Ti50Al50) were investigated. Phase transformation at presence of two PCA was: at first, powder mixture was transformed to a metastable solid solution of Al in Ti lattice (disordered hcp) and then transformed to amorphous phase with increasing the alloying time. The results showed that the state and type of PCA is effective in expedition of mechanical alloying process. The metastable solid solution phase (dis. hcp) at presence of methanol was achieved more quickly than stearic acid was used. Changes in grain size, lattice strain, weight recovered and impurity content of milling parameters at presence of two different PCA were studied. At last with annealed of last product of alloying, the TiAl(γ) phase with high purity and nanostructured form were produced.