Effect of Mo and Ti on the microstructure and microhardness in AlCoFeNiMoTi high entropy alloys prepared by mechanical alloying and conventional sintering

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2020-04, Vol.31 (4), p.1693-1701
• Main Authors: Avila-Rubio, M.A., Baldenebro-Lopez, J.A., Soto-Rojo, R., Ceballos-Mendivil, L.G., Carreño-Gallardo, Garza-Montes-de-Oca, N.F., Baldenebro-Lopez, F.J.
• Format: Article
• Language: English
• Subjects: High entropy alloys; Mechanical alloying; Microhardness; Microstructure; Powder metallurgy
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2020.02.008

[Display omitted] •High Entropy alloys of AlCoFeNiMo, AlCoFeNiTi and AlCoFeNiMoTi were produced by mechanical alloying.•Ti or Mo additions favor the formation of solid solutions BCC-type.•Ti additions favor the consolidation and sintering process.•Simultaneous additions of Mo and Ti encourage the hardness in the systems studied. In this investigation, the synthesis of equiatomic AlCoFeNi, AlCoFeNiMo, AlCoFeNiTi, and AlCoFeNiMoTi high entropy alloys, fabricated by mechanical alloying and conventional sintering processes is presented aiming to elucidate the effect of Mo and Ti additions on the properties of the AlCoFeNi base system. X-ray diffraction studies revealed that after 15 h of milling, only BCC and FCC structures were formed. It was also found that by increasing the crystallite size after sintering, phase transformations and composition variations were observed for all the systems studied but BCC and FCC structures prevailed. Further, the addition of the different alloying elements had a significant effect on the microhardness of the HEAs and particularly, the addition of Mo and Ti to form the AlCoFeNiMoTi system presented the highest value of 894 HV0.2. Finally, it was also found that Mo- containing alloys presented considerable porosity.