Effects of Cu addition on plasticity of Fe-6.5Si (wt.%) alloy at temperatures below 550 °C. (May 2020)

• Record Type: Journal Article
• Authors: Cheng, Z.Y.; Liu, J.; Xiang, Z.D.; Jia, J.; Bi, Y.J.
• Is Part Of: Intermetallics. Volume 120(2020:May)
• Publication Date: 2020-05
• Subjects: Magnetic alloys -- Brittleness and ductility -- Microalloying -- Order transformation -- Microstructure; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.106747
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: The plasticity of Fe-6.5Si (wt.%) alloys with additions of 0, 0.3, 0.5 and 0.7 wt% Cu was investigated by tensile tests at intermediate temperatures below 550 °C. It was found that the plasticity of Fe-6.5Si (wt.%) alloy increased with Cu addition to up to 0.3 wt%, but decreased with further increase in Cu addition. When the Cu addition was increased to 0.7 wt%, the plasticity of the alloy became lower than that for the alloy without Cu addition. The reduction of cross-sectional thickness of the tested specimens confirmed that the onset temperatures of brittle to ductile transition were about 90, 262, 304 and 400 °C for Fe-6.5Si (wt.%) alloys with Cu additions of 0.3, 0.5, 0 and 0.7 (wt.%), respectively. Microstructure analysis suggested that the solubility of Cu in the alloy was or higher than 0.3 wt%, but lower than 0.5 wt%. The Cu dissolution in the solid solution increased the plasticity of the Fe-6.5Si (wt.%) alloy as a result of the reduced degree of long-range order. Increasing Cu addition beyond the solid solution limit caused the Cu-rich phase precipitation at grain boundaries, which embrittled the grain boundaries and hence severely reduced the plasticity of the alloy. Graphical abstract: Image 1 Highlights: The degree of long-range order in the alloy was calculated by selected area electron diffraction and theoretical analysis. Microstructure analysis suggested that the solubility of Cu in the alloy was or higher than 0.3 wt%, but lower than 0.5 wt%. The dissolved Cu improved the plasticity of the alloy as a result of the reduced degree of long-range order. Cu addition beyond solubility limit caused Cu-rich precipitates at grain boundaries and reduced the plasticity of the alloy.