| Milling media of steel and partially stabilized zirconia(PSZ) were used to produce Mo_5Si₃ by mechanical alloying(MA) of Mo-37.5 at%Si powder mixture. The effect of milling medium materials on MA of the powder mixture has been investigated by SEM, XRD, DTA and in-situ thermal analysis. The homogeneity of the powder mixture, the reaction rate and the end-product markedly depended upon the milling medium materials. MA of the powder mixture by steel ball-milling produced the homogeneous structure faster than by PSZ ball-milling. The formation of Mo_5Si₃ by PSZ ball-milling occurred after 15hr of MA and was characterized by a slow reaction rate as Mo, Si and Mo_5Si₃, coexisted for a long period of milling time. The formation of any new phase by steel ball-milling, however, did not occur even after 96hr of MA. DTA and annealing results demonstrated that Mo and Si were transformed into Mo_5Si₃, phase after heating the powder specimen steel ball-milled for 24hr to 1040℃ Mo and Si were transformed into Mo5Si₃ and a little Mo_5Si₃ after heating the powder specimen PSZ ball-milled for 12hr to 1040℃. The formation of Mo_5Si₃ by mechanical alloying of the powder mixture and the reaction rate seemed to depend upon the milling medium materials (steel and PSZ) as well as the thermodynamic properties of Mo_5Si₃, compound. |
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