• Navazani, Mohammad
• Kada, Sitarama Raju
• Barnett, Matthew R.
• Fabijanic, Daniel

Abstract

<jats:p>A family of Al<jats:sub>x</jats:sub>Cu<jats:sub>y</jats:sub>CrFeMnNi (x=0, 0.15, 0.3, 0.6, 0.9 and y=0, 0.07, 0.14) high entropy alloys (HEA) were arc cast and then heat treated for 24h at 1100֯C-1150֯C followed by water quench. The microstructure of low Al alloys (Al<jats:sub>0</jats:sub>Cu<jats:sub>x</jats:sub> and Al<jats:sub>0.15</jats:sub>Cu<jats:sub>x</jats:sub>) consisted of FCC and BCC phases. Al<jats:sub>0.3</jats:sub>Cu<jats:sub>x</jats:sub> showed an additional ordered precipitate phase. High Al alloys (Al<jats:sub>0.6</jats:sub>Cu<jats:sub>x</jats:sub> and Al<jats:sub>0.9</jats:sub>Cu<jats:sub>x</jats:sub>) consisted of two BCC phases rich in Cr-Fe and Ni-Al. In the present study, the phases formed in the microstructures were evaluated in light of valence electron concentration (VEC), Hume-Rothery (H-R) and degree of partitioning. Although VEC successfully predicts the impact of Al and Cu on the trend of FCC-BCC phase formation, the parameter does not accurately predict the structure of high Al alloys. A good agreement was observed between H-R rules prediction and the experiments which might be ascribed to the high temperature equilibrium phases developed by the heat treatment. As per these criteria, increasing Cu (up to 3at.%) and decreasing Al promote formation of solid solution phases. Adding minor amounts of Cu avoids the Cu partitioning that besets high Cu HEAs.</jats:p>

Topics

• phase
• experiment
• precipitate
• water quench