Optimization and Characterization of Home Made Ball Mill for Preparing Nano-sized Tungsten Heavy Alloy

A mechanical home made ball mill was constructed in order to prepare
nano crystallite size from 90W-7 Ni-3Fe heavy alloy. The parameters of the
mechanical alloying process such as milling speed, milling medium, charge
ratio and the filling ratio were varied in order to find their influence on the mill
efficiency. It was found that the optimum parameters for the milling process at
which the crystallite size decreased faster, the contaminations are minimized,
the milling speed is adequate and the filling factor is justified are only obtained
by using; rods as a milling medium instead of using balls, milling speed to be
175 rpm, charge ratio is 20:1 and the filling factor is 30 %. XRD was taken for
all the samples milled at different times in order to see the different XRD
pattern steps of the alloy formation. From Rietveld refinements it was possible
to get the structural parameters, the crystallite size and the microstrain. These
results were correlated with each other and with similar results obtained from
the TEM. The energy dispersive X-Ray (EDX) results confirmed the weight
percentage of the different elements and the homogeneity of the elemental
powders in the resulting alloy.