{'fraction_non_alphanumeric': 0.018095238095238095, 'fraction_numerical': 0.013333333333333334, 'mean_word_length': 5.487654320987654, '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}}
Microstructural origins of corrosion in a 20% SiCp/2124 aluminium alloy metal matrix composite

The microstructure of a metal matrix composite (MMC) consisting of 20 wt% 3 μm SiC particles in a 2124 Al alloy matrix has been examined and the relationship to corrosion pitting processes investigated. Standard bulk corrosion tests show that the MMC forms a higher density of pits than the unreinforced alloy, although the overall performance is similar as the pits are shallower. In a new addition to conventional characterization techniques, transmission electron microscopy samples have been directly subjected to ‘flash’ corrosion treatment and subsequently examined. This technique is shown to be effective in studying the initiation of pits. The SiC particles and the widespread 9 intermetallic precipitates are shown to play little, if any, role. A sparse population of features introduced during powder processing and consolidation procedures, probably linked with strong magnesium segregation, is suggested to be responsible for pit initiation.