Influence of length-scales on spatial distribution and interfacial characteristics of B4C in a nanostructured Al matrix. (1st May 2015)

• Record Type: Journal Article
• Authors: Jiang, Lin; Wen, Haiming; Yang, Hanry; Hu, Tao; Topping, Troy; Zhang, Dalong; Lavernia, Enrique J.; Schoenung, Julie M.
• Is Part Of: Acta materialia. Volume 89(2015)
• Page Start: 327
• Page End: 343
• Publication Date: 2015-05-01
• Subjects: Metal matrix composites -- Nanoparticles -- Interface structure -- Interface chemistry -- Grain growth; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2015.01.062
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: To provide fundamental insight into the influence of length scales on the spatial distribution and characteristics of ceramic/metal interfaces in nanostructured metal matrix composites, we studied an Al alloy reinforced with a broad size distribution of B4 C particles, ranging from several nanometers to submicrometers. The B4 C was incorporated into an ultrafine grained Al matrix using cryomilling and thermomechanical consolidation. The characteristics of the B4 C/Al interface, namely the local chemistry and interfacial structure, were studied in detail using transmission electron microscopy (TEM) and atom-probe tomography. Results reveal significant differences in these characteristics as a function of particle length scale. A significant proportion (∼40%) of B4 C nanoparticles was located intragranularly, i.e., within ultrafine grain interiors, whereas submicron B4 C particles were surrounded by multiple Al grains, creating intergranular interfaces. Mg–O–N layers, Al2 O3 nanoparticles and amorphous regions were observed at the intergranular interfaces, whereas most of the intragranular interfaces were semicoherent and free of other phases or segregation. By combining crystal structure modeling and high-resolution TEM, a specific orientation relationship was identified for the intragranular interfaces: (1 −1 1)Al // ( 0 2 4 ) B 4 C, 3.4° angle between (0 0 2)Al and ( 0 0 3 ) B 4 C, and 7.8° angle between (2 −2 0)Al and ( 0 2 1 ) B 4 C . Mechanisms related to length scale effects on the formation of intragranular versus intergranular interfaces and corresponding structures and chemistries are discussed, as well as the implications of these interface characteristics on strength and ductility.