Comparative study between two die cast methods for processing Cu–Zr–Al bulk metallic glasses

摘要

The composition of a glass former alloy and the cooling rate are both extremely important to determine the maximum glassy or critical thickness of a sample under a specific processing technique. This work compares the suction casting and the centrifugal casting techniques for processing two Cu–Zr–Al bulk metallic glasses where the main characteristics evaluated were the mold-filling ability, the average time per cycle, the oxygen contamination and the maximum thickness on which the glassy phase was obtained. The Cu–Zr–Al system was chosen due to its high glass forming ability, which is extensively reported in the literature. The wedge shape sample was chosen because it allows the evaluation of different thicknesses (hence cooling rates) at the same sample. Results revealed that the copper mold centrifugal casting had a higher oxygen contamination, whilst the mold-filling ability was similar in both processes. Also, for the centrifugal casting technique, the average time per cycle was higher and the maximum thickness in which glassy phase could be obtained was lower. A brief analysis considering the oxygen contamination on these alloys is also presented here, revealing the extreme importance of controlling this parameter.