Effects of Hot Extrusion Temperature Conditions on the Hardness and Electrical Conductivity of Rapidly Solidified Al-Fe Alloys

• Published in: Materials Vol. 16; no. 14; p. 5050
• Main Authors: Kobayashi, Ryohei, Funazuka, Tatsuya, Maeda, Toru, Shiratori, Tomomi
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 17-07-2023; MDPI
• Subjects: Alloy powders; Alloys; Aluminum; aluminum alloy; Aluminum base alloys; Analysis; Annealing; Atomizing; Electric conductors; Electric properties; Electrical conductivity; electrical conductor; Electrical properties; Electrical resistivity; Extrusion billets; Extrusion dies; Extrusions; Ferrous alloys; Hardness; Heat resistance; Heat treating; Heat treatment; Heating; High temperature; Hot extrusion; Hot pressing; Intermetallic compounds; Iron; Mechanical properties; mechanical property; Plasma sintering; Powder metallurgy; Powders; Rapid solidification; Raw materials; Sintering (powder metallurgy); Specialty metals industry; Temperature; Weight reduction; Japan; electrical conductor; hot extrusion; powder metallurgy; mechanical property; aluminum alloy
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16145050

Rapidly solidified Al-Fe alloys produced by hot extrusion are a promising replacement for copper-based electrical conductors because of their light weight. However, the effects of the extrusion temperature conditions on the mechanical and electrical properties of extruded materials are unknown. The present work investigated the effects of billet preheating temperature, in situ temperature during extrusion, and additional heat treatment after extrusion on hardness and electrical conductivity. An air-jet atomized Al-2.3%Fe alloy powder was pre-sintered into cylindrical billets and then hot-extruded. The hardness of the extrudates decreased as the in situ temperature during extrusion increased above 650 K. The billet preheating temperature affected the in situ temperature during extrusion. Additional annealing after extrusion decreased the hardness. The cause of the decrease in hardness was coarsening of the grain of the aluminum matrix. The electrical conductivity increased with higher billet preheating temperatures before extrusion or additional annealing after extrusion; however, an in situ temperature rise for a few seconds during extrusion did not affect the conductivity. The increase in electrical conductivity was considered to be caused by a decrease in the amount of solute iron, which requires holding the material at a high temperature for longer than several minutes.