{'fraction_non_alphanumeric': 0.02316076294277929, 'fraction_numerical': 0.006811989100817439, 'mean_word_length': 5.331896551724138, '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}}
Creep properties and failure mechanisms of aluminum alloy and aluminum matrix silicon oxide nano-composite under working conditions in engine pistons

In the present article, creep properties and also failure mechanisms of two aluminum alloys, were experimentally investigated under working conditions in engine pistons. There materials included the AlSi12CuNiMg piston aluminum alloy and the aluminum matrix silicon oxide nano-composite. The nano-composite was made by stir-casting of the aluminum alloy and 2 wt% of nano-particles. Then, creep standard specimens were tested in a force-controlled condition and under 100 MPa of the applied stress and at 250 °C of the temperature. Results of the optical microscopy implied that the microstructure feature for both aluminum alloys was almost similar. Nano-particles had no significant effect on the microstructure of the aluminum alloy. Results of creep testing demonstrated that the lifetime reduced, when nano-particles were added to the aluminum alloy. Since nano-particles caused to a stress concentration based on flaked-shape silicon particles and to have more intermetallic phases. In other words, local agglomerations of 2 wt% nano-particles led to decrease creep properties of the aluminum alloy. According to images of field emission scanning electron microscopy, both materials had brittle fracture behaviors. Since on fracture surfaces, there were cleavage and quasi-cleavage marks, as failure mechanisms.