{'fraction_non_alphanumeric': 0.020351526364477335, 'fraction_numerical': 0.004625346901017576, 'mean_word_length': 5.044692737430168, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Mechanisms of Powder Milling Investigated by X-ray Diffraction and Quantitative Metallography

The powder milling (or mechanical alloying) process was investigated by milling pure Fe, single-phase Fe 60 Al 40 and Ni 3 Al powders with two different mills. To characterize the process, coherence lengths and rms-strains, using X-ray peak broadening analysis, and the shape factor and size of powder particles, using quantitative metallography, were measured. From the temporal evolution of these quantities it was concluded that the milling process can be subdivided into three periods. In the first period only plastic deformation occurs, followed by fracture of deformed particles. The second period is characterized by the onset of welding and a decrease in the amount of plastic deformation. The third, final and longest period is dominated by an equilibrium of fracture and welding mechanisms, whereas plastic deformation plays only a minor role. The time scale and the path leading to the final microstructure of the powders is shown to depend on the type of the mill utilized.