Rheo-Squeeze Casting of High-Silicon Aluminium Alloy Pipes with Gradient Structures and Their Mechanical Properties

Abstract

Three different compositions of high-Si Al alloy pipe, with a gradient structure, were produced through semi-solid rheological squeeze casting, the microstructural characteristics of which were investigated. The mechanism of gradient structure formation and the effect of acicular Fe-rich phases on liquid segregation were revealed. Meanwhile, the crystal structures of the Al 4 FeSi 2 and Al 15 (Fe, Mn) 3 Si 2 phase were elucidated. The relationship between the volume fraction of hard particles in the pipe wall and the macro-hardness was established. Wear resistance tests of the inner surfaces of the pipe walls, and tensile strength tests at different positions around the pipe walls, showed that the δ-Al 4 FeSi 2 phase (acicular Ferich phases) reduced the wear resistance and the tensile strength of the alloy. In this study, the gradient distribution of the hard particles caused the outside of the pipe wall to have a higher tensile strength.

Effect of Sintering Process on Microstructure and Properties of Al-Si Alloy Made by Powder Metallurgy for Electronic Packaging Application

“…Highquality packaging materials should possess strong mechanical properties, low coefficients of thermal expansion (CTE), and high thermal conductivity (TC). Aluminum-high Silicon (Al-Si) alloy exhibits favorable TC, high specific strength and stiffness, good plating compatibility with gold, silver, copper, and nickel, weldability to substrates, and ease of precision machining [2,3]. Furthermore, it is readily available, environmentally benign, non-toxic, and easily recyclable [4][5][6].…”

Evaluation of Microstructural Characteristics of High-Si Al Alloy Cylindrical Samples Produced by Rheological Squeeze Casting with Bottom-Up Filling and Flow State Analysis of the Alloy Semi-Solid Slurries

“…Solidification microstructures of this series of alloys are mainly comprised of primary Si, primary α-Al, and eutectic phases 1,2 . The size and shape of primary Si have a large influence on the final properties (both mechanical and wear properties) of hypereutectic Al-Si alloys 3,4 . Therefore, it is necessary to conduct modification treatment to refine and homogenize the primary Si phases through melt controlled cooling technology for realizing the application of this alloy [5][6][7] .…”