Hardness and Young's modulus of Al3Yb single crystal studied by nano indentation. (December 2020)

• Record Type: Journal Article
• Authors: Li, Haonan; Gao, Kunyuan; Gao, Chunlai; Ding, Yusheng; Xiong, Xiangyuan; Wu, Xiaolan; Huang, Hui; Wen, Shengping; Nie, Zuoren; Zhang, Qian
• Is Part Of: Intermetallics. Volume 127(2020:Dec.)
• Publication Date: 2020-12
• Subjects: A. Aluminides -- B. Anisotropy -- B. Elastic properties -- E. mechanical properties -- Theory -- F. Nanoindentation -- F. orientation imaging microscopy; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.106980
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract : The orientation, hardness and Young's modulus of Al3 Yb single crystal were analyzed using the electron back scatter diffraction (EBSD) and nanoindentation techniques, combined with the first principles calculations. The Al3 Yb single crystal of about 1 mm size could be obtained by heating hypereutectic Al-38.5 (wt%)Yb alloy to liquid state and cooling to room temperature at 60 °C/h. The results showed that the hardnesses of the Al3 Yb single crystals oriented in (318), (023), (213), (112) and (122) directions varied between 5.4 ± 0.1 and 5.7 ± 0.1 GPa, and the reduced modulus were between 131.9 ± 1.6 and 140.5 ± 3.9 GPa. First principles calculations by assuming standard Yb pseudopotential with 4f electrons showed that the elastic constants of C11, C12 and C44 were 149.4, 32.94 and 66.59 GPa, respectively, and the Poisson's ratio was 0.161. Based on these calculated elastic constants and Poisson's ratio and the reduced modulus values, the Young's modulus of the Al3 Yb single crystal was determined to be between 148.4 ± 2.3 and 154.9 ± 2.3 GPa for different orientations and the anisotropy coefficient (A) was 1.17 ± 0.01. Highlights: The large size Al3 Yb single crystal was obtained by hypereutectic alloy slow cooling down from liquid. The hardness and composite response modulus were analyzed by nano indentation. The elastic properties were calculated by first principles using standard pseudopotential. Young's modulus of Al3 Yb was obtained from the composite response modulus data and calculated Poisson's ratio.