The Effect of Al and Ti Additions on Solid Solution Strengthening and Precipitation Hardening in CoNiFe Medium-Entropy Alloys

• Published in: Materials Vol. 16; no. 18; p. 6297
• Main Authors: Bała, Piotr, Górecki, Kamil, Dziurka, Rafał, Kozieł, Tomasz
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2023; MDPI
• Subjects: aging; Alloys; Aluminum; Cobalt; Electric arc furnaces; Equilibrium; Grain size; heat treatment; High entropy alloys; Intermetallic compounds; Investigations; Iron; mechanical properties; Medium entropy alloys; Microscopy; microstructure; Nickel; Precipitation hardening; Software; Solid solutions; Solidification; Solution heat treatment; Solution strengthening; Specialty metals industry; Strain hardening; Temperature; Titanium; United States > US
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16186297

The effect of Al and Ti additions on the microstructure and properties of CoNiFe alloys was studied in this paper. The investigations were conducted on four specially designed and produced arc furnace alloys (from 3 to 5 components, with medium to high entropy). Samples in various states were analyzed, i.e., as-cast, after homogenization, after solution heat treatment, and after solution heat treatment and aging. The obtained samples were characterized by: SEM observations, EDS, XRD, TEM analyses, and finally, hardness measurements. The solid solution strengthening coming from the addition of 5 at. pct. Al was negligible, while the effect from the 5 at. pct. of Ti addition was significant. The precipitation hardening effect related to the presence of the (CoNi)3Ti phase caused by the Ti addition is comparable with the total effect of the Al and Ti addition, which caused the precipitation of (NiCo)3AlTi.