Preparation and characterization of in-situ Al-AlXNiY composites via reactive infiltration

• Published in: Journal of alloys and compounds 2019-04, Vol.780, p.829-845
• Main Authors: Rasouli, Mohsen, Akhlaghi, Farshad, Ojo, O.O., Paidar, Moslem
• Format: Article
• Language: English
• Subjects: Al3Ni2 composite; Fracture; Fracture toughness; Heat treating; Heat treatment; In-situ Al3Ni; Infiltration; Intermetallic compounds; Mechanical properties; Microhardness; Microstructure; Morphology; Nickel; Particulate composites; Pickling; Reactive infiltration; Solid state; Tensile properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.11.408

In-situ Al-AlxNiy composites were prepared by reactive infiltration method via reaction between a preform of 12 strands of commercially pure Ni wire (99%) having 150 μm diameter and molten commercially pure aluminum (99.6%), with a subsequent heat treatment. The microstructures and compositions, microhardness, tensile properties and fracture behaviors of the composites were analyzed and compared with that of pure Al and Al-1.92%Ni alloy. The results reveal that acid pickling effect enhances homogeneous infiltration and solid-state inter-diffusion into the Ni wires. Prolonged heat treatment time (300 min) promotes homogeneous solid-state inter-diffusion around the Ni core in the composite subjected to sub-eutectic heat treatment (625 °C). The thickness of intermetallic compounds increases from 5.5 to 24.9 μm (for samples heated below eutectic point) and 550–1600 μm (for samples heated above eutectic point) as the heat treatment holding time increases (15–60 min). Ring-shaped Al3Ni2 around the Ni wires and in-matrix rosette-like Al3Ni ensue in the composites formed at under and above eutectic heat treatment respectively. Sub-eutectic heat treatment of the composite produced the better tensile strength (76.99 MPa) and toughness (230.56 KJm−3) as compared to the composite heat treated above the eutectic temperature (70.09 MPa and 90.06 KJm−3). The fracture morphologies agree with the tensile results. •Al-AlxNiy composites were produced by reactive infiltration.•Amount of solid-state diffusion and intermetallic growth are controlled by heat treatment holding time.•Sub-eutectic heat treatment improved the properties of Al-AlxNiy composite.•Acid pickling enhanced homogeneous solid-state diffusion.