Modeling

From the previous description it is easy to realize that MA is a complex process. Like any other process, modeling of MA is carried out to identify the salient factors affecting the process and to establish process control instrumentation. By modeling the process effectively, it is possible to lower the number of actual experiments to be conducted to optimize the process and achieve a particular application.

The number of variables involved in the MA process is very large. For a particular alloy system, the variables include the type of mill, intensity of milling, type of milling media, ball-to-powder weight ratio, the atmosphere under which the powder is milled, purity of the powders, milling time, milling temperature, and nature and amount of the PCA used. These have a significant effect on the constitution of the powder. Even on a local scale, the nature of impacts between two balls, the frequency of impacts, and the amount of powder trapped between two balls during a collision could vary from point to point. Thus, modeling the MA process is a difficult task. In spite of this, some attempts have been made (Ref 28, 29, 30) and moderate success has been achieved in modeling the mechanics of the process. From the actual experiments conducted, attempts have been made to correlate the phases formed with the process parameters during milling. But, the ability to predict the final chemical constitution of the powder (type and description of phases formed) has not been achieved. It should be realized that due to the stochastic nature of the MA process, it is difficult to make absolute predictions.

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