Issue 35

S. Lesz et alii, Frattura ed Integrità Strutturale, 35 (2016) 206-212; DOI: 10.3221/IGF-ESIS.35.24 211 Figure 5 : SEM images of the fracture morphology of Fe 36 Co 36 B 19 Si 5 Nb 4 alloy rod with diameter of  =4 mm after compressive fracture; a – main view: vein and smooth pattern regions, b – image of fracture near the core of rod, smooth and vein patterns, c, d – image of fracture outside surface, vein patterns, d – magnified veins from the area as point in (c). White arrows indicate the direction after the initial of cracking and direction at a further state of cracking. C ONCLUSIONS he structure of surface rods with  =2, 3 and 4 mm in diameter of Fe 36 Co 36 B 19 Si 5 Nb 4 alloy is amorphous. The Fe- based BMG rods exhibits elastic strain – ε , Young’s modulus - E , compressive stress - σ c and unitary elastic strain energy – U u , of 0.75 to 0.94 %, 105 to 191 GPa, 790 to 1794 MPa and 17 to 25 kJ/m 2 , respectively. Fracture morphology of rods after compressive fracture has been different on the cross section. Two characteristic features of the compressive fracture morphologies of metallic glasses (MGs) were observed in samples: smooth region and the vein pattern. The presence of these fracture morphologies indicate that the Fe-based BMG of this study classifies itself as a brittle amorphous material. The results of these investigations suggest that the significant factor to control the structure, mechanical properties and fracture morphology of the Fe 36 Co 36 B 19 Si 5 Nb 4 BMG is cooling rate. Thus is factor has an instructional importance for the optimization of materials’ performance. R EFERENCES [1] Klement, W., R. H. Willens, Duwez, P., Non-crystalline structure in solidified gold–silicon alloys, Nature, 187 (1960) 869-870. DOI: 10.1038/187869b0. [2] Chen, H. S., Turnbull, D., Formation, stability and structure of palladium-silicon based alloy glasses, Acta Metallurgica, 17 (1969) 1021-1031. DOI: 10.1016/0001-6160(69)90048-0. T