Issue 35

A. Pawełek et alii, Frattura ed Integrità Strutturale, 35 (2016) 21-30; DOI: 10.3221/IGF-ESIS.35.03 29 2. The transition from one to another kind of fracture is correlated with the stress and AE parameters achieve minimal values just at the same temperature 150°C. 3. The AE technique can be helpful in further research of the changes in fracture character at elevated and/or higher temperatures. 4. The fracture of compressed Mg4Li5Al alloy at room temperature is related to the strain localization in shear bands, and it is characterized by growth and development of the crack path. 5. In Mg4Li4Zn alloys tensile tested at elevated temperatures, prepared by casting of raw materials, the effect PL does not occur and the plastic flow is rather of stable character, and the fracture, being mostly of intergranular character, as well as the AE behavior are not essentially changed. A CKNOWLEDGMENTS he studies were financially supported by Polish National Science Centre (project in competition OPUS 4, grant No 2012/07/B/ST8/03055), and also by the Slovak Academy of Sciences - project VEGA No 2/0186/14. R EFERENCES [1] Fujiwara, S., Abiko, K., Ductility of Ultra High Purity Copper, Journal de Phys. IV, Coll. C7, 5 (1995) C7-295. [2] Misra, K., Prasad, S., On the dynamic embrittlement of copper-chromium alloys by sulphur, J. Mat. Sci., 35 (2000) 3321-3325. DOI: 10.1007/s10853-011-5728-9. [3] Kanno, M., Shimodaira, N., Improvement in ductility at intermediate temperatures by a small addition of yttrium in a Cu-30%Zn alloy, Scripta Metall., 21 (1987) 1487-1492. [4] Yamagata, H., Izumi, O., Deformation and Ductility of α Brass Single Crystals at Elevated Temperatures, J. Jap. Inst. Metals, 42 (1978) 1012-1019. [5] Kudela, S., Pawełek, A., Ranachowski, Z., Piątkowski A., Kudela S. Jr., Ranachowski P., Effect of Al alloying on the Hall-Petch strengthening and AE in compressed Mg-Li-Al alloys before and after HPT processing, Kovove Mater., 49 (2011) 271–277. DOI: 10.4149/km 2011 4 271 [6] Pawełek, A., Jasieński, Z., Kúdela, S., Piątkowski, A., Ranachowski, P., Rejmund, F., Acoustic emission in channel-die compressed Mg-Li-Al alloys reinforced with short ceramic fibres, in: J. Jerz, P. Šebo, M. Zemankova (Eds.), Proceedings of the Int. Conf. on Advanced Metallic Materials, pp.229-234, Smolenice, Slovakia, November 5-7, 2003; Influence of β phase on mechanical and acoustic behaviour of Mg-Li-Al alloys, pp.225-228: ibidem. [7] Kuśnierz, J.; Pawełek, A.; Ranachowski, Z.; Piątkowski, A.; Jasieński, Z.; Kúdela, S. & Kúdela, S., Jr., Mechanical and Acoustic Emission Behavior Induced by channel-die Compression of Mg-Li Nanocrystalline Alloys Obtained by ECAP Technique, Reviews on Advanced Materials Science, 18 (2008) 583-589. [8] Pawełek, A., Mechanical behavior and plastic instabilities of compressed Al metals and alloys investigated with application of intensive strain and acoustic emission methods, in: Zaki Ahmad (Ed.), Recent Trends in Processing and Degradation of Aluminium Alloys, Published by InTech, Chapter 11 (2011) 263-298. [9] Pawełek, A., Ozgowicz, W., Ranachowski, Z., Kúdela, S., Piątkowski, A., Kúdela, S., Jr., Ranachowski, P., Micro- cracking and Deformation Processes in Compressed Mg Alloys Matrix Composites Investigated with Acoustic Emission Method, Proceedings of the Int. Conf. on Materials and Technology (22ICM&), October 20-22, 2014, Portorož (Slovenia), Materiali in Tehnologije, (2015): in press. DOI: 10.1007/s10973-011-1375-2 [10] Pawełek, A., Piątkowski, A., Jasieński, Z., Pilecki, S., Acoustic Emission and Strain Localization in FCC Single Crys- tals Compressed in Channel-Die at Low Temperature, Z. Metallkde., 92 (2001) 376-381. [11] Pawełek, A., On the Dislocation-Dynamic Theory of the Portevin-Le Chatelier Effect , Z. Metallkde., 80 (1989) 614- 618. [12] Jasieński, Z., Pawełek, A., Piątkowski, A. Ranachowski, Z., Twinning and shear band formation in channel–die compressed silver single crystals identified by Acoustic Emission method, Proceeding of 10 th French-Polish Colloquium, Paris (France), 20-21 May 2008, Archives of Metallurgy and Materials, 54 (2009) 29-33. DOI: 10.3139/146.110033. T