Twinning and orientation relationships of the monoclinic θ-Al45(Mn, Cr)7 phase in an Al–Mg alloy containing Mn. (May 2021)

• Record Type: Journal Article
• Authors: Xiao, Xiaoling; Liu, Hongwei; Vogel, Florian
• Is Part Of: Intermetallics. Volume 132(2021)
• Publication Date: 2021-05
• Subjects: θ-Al45(Mn, Cr)7 phase -- Orientation relationship -- Twin -- TEM -- Al–Mg alloy; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2021.107152
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: The spherical-like θ-Al45 (Mn, Cr)7 particle having a monoclinic structure is observed in an Al–Mg alloy using TEM. Two types of twins with different twin directions are found in these θ-Al45 (Mn, Cr)7 particles. One type is shown to be a ( 1 ‾ 11 ) twin with ( 1 ‾ 11 ) plane serving as the twinning plane and the shear direction is η1 = [ 1 2 ‾ 3 ] ; the other type is seen to be a ( 1 ‾ 10 ) orientation twin with ( 1 ‾ 10 ) plane acting as the coherent plane. At least six different orientation relationships between the θ-Al45 (Mn, Cr)7 particles and the α-Al matrix are observed. These relatively complicated orientation relationships are attributed to the pseudo ten-fold symmetric building block of the θ phase viewed along the [101] axis. The possible formation mechanisms of these twins are discussed based on a crystallographic consideration. Highlights: Two types of twins with different twin directions are found in the θ-Al45 (Mn, Cr)7 particles. One is ( 1 ¯ 11 ) twin with the ( 1 ¯ 11 ) plane serving as the twinning plane, and the shear direction is η1 = [ 1 2 ¯ 3 ] QUOTE with, this ( 1 ¯ 11 ) twin is a compound twin. The other is ( 1 ¯ 10 ) orientation domain with ( 1 ¯ 10 ) plane acting as the coherent plane, and is verified to be type II twin. Multiple orientation relationships between the FCC structure α-Al matrix and the θ-Al45 (Mn, Cr)7 particle were observed and disscussed.