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Talks and Poster Presentations (without Proceedings-Entry):

G. Requena, E. Marks, H.P. Degischer, E. Boller:
"Enhanced Creep Resistance by 3D connectivity of short fibre reinforcement in AlSi alloys";
Talk: 5th International Conference on Cree, Fatigue and Creep-Fatigue Interaction, Kalpakkam, India (invited); 09-24-2008 - 09-26-2008.



English abstract:
The long-term creep behaviour of a eutectic AlSi12CuMgNi alloy reinforced with 15 vol% of Al2O3 short fibres was investigated at 300°C for loads between 15 and 70MPa. Load changes were imposed for periods of a few hundred hours during the creep tests. The stationary creep rate after periods at different loads decreased significantly with respect to the initial stationary creep rate prior to the load change. The evolution of the 3D microstructure during creep was investigated by means of synchrotron microtomography. The results show that the short fibres are connected by Si bridges and that this interconnectivity increases during creep exposure. The effect of this increase of interconnectivity on the creep behaviour was studied by means of 3D finite elements analysis based on the actual microstructure of the composite in two conditions: (1) at the beginning of the creep tests and (2) after more than 6000h of creep exposure. The results reveal a Gaussian distribution of the applied load within the Al-matrix for both studied conditions. However, the initial condition presents a tail in the stress distribution curve with stresses higher than after more than 6000h of creep exposure. The simulations show that the increase in the creep resistance after long-term creep exposure is a consequence of the diffusion driven increase of the interconnectivity between the ceramic short fibres and the eutectic Si.

Created from the Publication Database of the Vienna University of Technology.