Abstract
In order to understand the deformation and fracture behavior of Nb-Si alloys, in-situ observation was conducted during bending of small specimens at room and high temperatures. Nb-Si alloy ingots containing 18.1 at.%Si, 1.5 at.%Zr and 100 ppmMg were prepared by arc melting, followed by uni-axial solidification in an optical floating zone apparatus and a heat-treatment to obtain Nb/Nb5Si3 two-phase microstructure. Chevron-notched specimens with a dimension of 1x2x10mm were used for in-situ observation of bending tests under a confocal laser scanning microscope (CLSM) at room temperature and at 1140 °C. At room temperature the Nb-Si alloy shows a fracture toughness of 8 MPa m1/2 and the crack propagation velocity seems to be not uniform, presumably due to the ductile Nb. At 1140 °C the toughness of the alloy was about 20 MPa m1/2 and slower plastic deformation prior to the cracking was observed. The SEM observation of crack surfaces revealed that plastic deformation of Nb enhances the toughness of the alloy.
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Miura, S., Tsutsumi, Y. & Mohri, T. In-situ observation of Nb/Nb5Si3 two-phase alloys during bending at various temperatures. MRS Online Proceedings Library 1295, 373–378 (2011). https://doi.org/10.1557/opl.2011.190
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DOI: https://doi.org/10.1557/opl.2011.190