Synthesis and properties analysis of char-reinforced Al-13.5Si-2.5Mg alloy composites

• Published in: Journal of materials science Vol. 33; no. 4; pp. 1003 - 1013
• Main Authors: EJIOFOR, J. U, REDDY, R. G, OKORIE, B. A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 15.02.1998; Springer Nature B.V
• Subjects: Activated sintering; Aluminum base alloys; Aluminum carbide; Applied sciences; Composite materials; Dimensional changes; Dispersion hardening metals; Exact sciences and technology; Materials processing; Materials science; Mechanical properties; Metals. Metallurgy; Net shape; Powder metallurgy. Composite materials; Production techniques; Synthesis; Reaction sintering; Shell; Aluminium base alloys; Silicon alloy; Manufacturing process; Coal; Magnesium alloy; Coconut; Mechanical properties; Hardness; Composite material; Dispersion strengthened metal
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004320113625

The re-evaluation of previous and existing methods in materials processing is becoming ever more critical because of processing and starting materials cost factors. A study on the synthesis and properties investigation of hypereutectic Al–13.5Si–2.5Mg alloy reinforced with carbon chars using coconut shell as the organic precursor has been carried out. The low-cost, double compaction solid-state technique was used. Reinforcing the hypereutectic alloy with coconut shell char particles (size:<140 μm) at 2 vol % and consolidating by reaction sintering at 600 °C in vacuum for 15 min, followed by near net-shape compaction at 250 MPa, increased the hardness of the alloy 6% while reducing its strength (UTS) by only 3%. The use of palm kernel shell char as the dispersed phase was found to yield identical results. At 2 vol % char, the mechanical properties, sintered density and dimensional changes were optimally found to be suitable for lightweight anti-friction electromechanical applications. Attempts to reinforce the alloy with 2 vol % coconut shell chars activated in CO2 reduced its strength in the range of 19 to 26% at different burn-off percentages. This is attributed to the higher amount of oxide products formed during the activation process. At 600 °C, formation of the brittle Al4C3 phase in the different sintered composites containing activated and unactivated chars was identified by X-ray studies. © 1998 Chapman & Hall