Livarski vestnik 52 / 2005 Nr. 3
G. Lojen, I. Anžel, A. Kneissl, A. Križman, E. Unterweger, B. Kosec, M. Bizjak:
Microstructure of Fast Cast Ribbons from Shape Memory Alloys Cu-Al-Ni
W. Eichlseder, F. Gruen, J. Froeschl:
Optimisation of Cast Components Regarding Fatigue Strength
G. Lojen, I. Anžel, A. Kneissl, A. Križman, E. Unterweger, B. Kosec, M. Bizjak:
Microstructure of Fast Cast Ribbons from
Shape Memory Alloys Cu-Al-Ni
Shape Memory Alloys Cu-Al-Ni
Summary
Shape memory alloys (SMA) Cu-Al-Ni are in the moment the one and only against degradation of memory properties that have good high temperature resistance SMA. Polycrystalline alloys are very brittle and attainable reversible deformation is generally very small. On the procedure melt spinning we can make very thin ribbons in as-cast state. With suitable parameters we can attain single-layer columnar microstructure with fibrous texture, which noticeable enlarge reversible deformation in longitudinally direction of ribbons.
At procedure free jet melt spinning we cast Cu-Al-Ni ribbons with 13, 14 and 15 m.% Al. Because of low thermal conductivity of alloys was not possible to simultaneously attain great width of ribbons, single-layer columnar structure and (except at 13 m.% Al) of single phase martensitic state. Irrespective of chemical composition is the microstructure single-layer columnar only at ribbons thinner from ca. 50µm , otherwise is two- or more layer with equal axis. Speed of cooling was unusually low, with regard to largeness of crystal grains, high under 103 K/s. In as cast state were single phase martensitic only ribbons with 13 m.%Al. With heat treatment at temperatures to 900 °C it was possible to improve microstructure only at ribbons with 13 and 14 m.% Al. But the needed temperature of annealing should be above 1000 °C, which is very near to solidus temperature of alloy. Ribbons from all alloys have shape memory in as cast state. By heat treated ribbons from alloy with 13 m.% Al we noticed two way shape memory allready after the first cycle of bending deformation in cold and heating without loading. We made investigations with support of Austrian fund for support of science investigations (Oesterreichischer Fonds zur Foerderung der wissenschaftlichen Forschung - FWF), projekt Nummer P14221.
Key words: shape memory alloys, Cu-Al-Ni, melt spinning, microstructure
At procedure free jet melt spinning we cast Cu-Al-Ni ribbons with 13, 14 and 15 m.% Al. Because of low thermal conductivity of alloys was not possible to simultaneously attain great width of ribbons, single-layer columnar structure and (except at 13 m.% Al) of single phase martensitic state. Irrespective of chemical composition is the microstructure single-layer columnar only at ribbons thinner from ca. 50µm , otherwise is two- or more layer with equal axis. Speed of cooling was unusually low, with regard to largeness of crystal grains, high under 103 K/s. In as cast state were single phase martensitic only ribbons with 13 m.%Al. With heat treatment at temperatures to 900 °C it was possible to improve microstructure only at ribbons with 13 and 14 m.% Al. But the needed temperature of annealing should be above 1000 °C, which is very near to solidus temperature of alloy. Ribbons from all alloys have shape memory in as cast state. By heat treated ribbons from alloy with 13 m.% Al we noticed two way shape memory allready after the first cycle of bending deformation in cold and heating without loading. We made investigations with support of Austrian fund for support of science investigations (Oesterreichischer Fonds zur Foerderung der wissenschaftlichen Forschung - FWF), projekt Nummer P14221.
Key words: shape memory alloys, Cu-Al-Ni, melt spinning, microstructure
JW. Eichlseder, F. Gruen, J. Froeschl:
Optimisation of Cast Components
Regarding Fatigue Strength
Summary
Regarding Fatigue Strength
Summary
Cast components offer a wide range of the design implementation of optimisation results. By combining fatigue life analysis and topology optimisation the optimum geometry concerning the fatigue life can be found. The first step is the fatigue life assessment of geometrically complex structures, which can be done by the finite element method. Based on these local stresses, taking into account the load spectra, damage values can be calculated. These damage values correspond to the fatigue lifetime of the structure under service conditions. The advantage of combining the proposed method is shown on several cast components.
Key words: topology optimisation, fatigue lifetime calculation, cast
Key words: topology optimisation, fatigue lifetime calculation, cast