Effect of rare earth cerium addition on the microstructure and tensile properties of hypereutectic Al–20%Si alloy

• Published in: Journal of alloys and compounds Vol. 562; pp. 25 - 32
• Main Authors: Li, Qinglin, Xia, Tiandong, Lan, Yefeng, Zhao, Wenjun, Fan, Lu, Li, Pengfei
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15-06-2013; Elsevier
• Subjects: Aluminum base alloys; Coarsening; Condensed matter: structure, mechanical and thermal properties; Deformation and plasticity (including yield, ductility, and superplasticity); Eutectic Si; Eutectics; Exact sciences and technology; Hypereutectic Al–20%Si alloy; Intermetallic compounds; Mechanical and acoustical properties of condensed matter; Mechanical properties; Mechanical properties of solids; Microstructure; Morphology; Physics; Primary Si; Rare earth Ce; Rare earth metals; Silicon; Mechanical properties; Rare earth Ce; Hypereutectic Al–20%Si alloy; Eutectic Si; Primary Si; Hypereutectic Al―20%Si alloy; Scanning electron microscopy; Aluminium base alloys; Ultimate strength method; Impurity density; XRD; Fine structure; Optical microscopy; Silicon alloys; Electron microprobe analysis; Cerium additions; Eutectic alloys; Microstructure; Tensile properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.02.016

► The microstructural characterization and tensile properties of hypereutectic Al–20%Si alloy with various concentration of Ce have been investigated. ► The primary Si crystals are significantly refined by adding rare earth Ce. ► The eutectic Si structure is obviously modified by adding rare earth Ce. ► The UTS and El of the alloy gradually improve with increasing concentration of Ce.
It is well known that the mechanical properties of hypereutectic Al–Si alloys are influenced by the size, morphology and distribution of primary and eutectic Si crystals. In the present work, the microstructure evolution and mechanical properties of hypereutectic Al–20%Si alloy with rare earth cerium (Ce) additions (0, 0.3, 0.5, 0.8 and 1.0wt.%) were investigated. The as-cast samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA) with wavelength dispersive spectroscopic (WDS). The microstructural observation showed that primary Si crystals were significantly refined from coarse polygonal and star-like shape to fine blocky shape with smooth edges and corners, and eutectic Si phases were modified from coarse platelet-like/needle-like structure to fine fibrous structure and discrete particles with increasing the addition contents of rare earth Ce. The mechanical properties were investigated by tensile test with various concentration of Ce. It was found that the ultimate tensile strength (UTS) and elongation (El) increased by 68.2% and 53.1%, respectively, due to decreasing of the size and changing of morphology on primary and eutectic Si crystals.