Influence of fine-scale B2 precipitation on dynamic compression and wear properties in hypo-eutectic Al0.5CoCrFeNi high-entropy alloy

Effect of heat treatments on microstructure and mechanical properties of Al0.5CoCrFeNi complex concentrated alloy

“…Wang et al [30,31] have reported the formation of high-temperature bcc(A2) phase in the interdendritic region of Al 0.5 CoCrFeNi alloy and its spinodal decomposition to bcc(A2) + bcc(B2) type of microstructure. However, the experimental results of this work support formation of the ordered bcc(B2) phase during solidification and its spinodal decomposition to bcc(B2 ) + bcc(A2) phases, which is in agreement with the thermodynamic calculations of Zhang et al [20], Gwalani et al [32], and experimental results reported by Rao et al [14].…”

“…Figure 11 shows the dependence of Vickers microhardness of dendrites and Vickers hardness of Al 0.5 CoCrFeNi alloy on the ageing time at the ageing temperatures of 800 and 900 • C. Both the microhardness HV m and hardness HV increase with increasing ageing time up to 5 h and then decrease at a longer ageing time. The ageing in fcc(A1) + bcc(B2) + σ phase field at an ageing temperature of 800 • C results in significantly higher microhardness and hardness values compared to those of the samples aged in fcc(A1) + bbc(B2) phase field at 900 • C. Assuming precipitation hardening theories reviewed by Ardell [35], the increase of HV m and HV can be attributed mainly to a higher volume fraction, smaller size and coherency of needle-like bcc(B2) precipitates forming at 800 • C compared to those forming during ageing at 900 • C. It should be noted that the measured Vickers hardness values for the samples aged at 800 • C are higher than those ranging from 245 to 285 reported for as-cast Al 0.5 CoCrFeNi alloy aged at temperatures ranging from 350 to 950 • C for 24 h [36] or those ranging from 258 to 302 after solution annealing at 1150 • C followed by ageing at 700 • C up to 80 h [32].…”

Understanding the Links between the Composition-Processing-Properties in New Formulations of HEAs Sintered by SPS

“…This BCC microstructure with coherent B2 precipitates has been observed in other HEAs containing Al and Ni [25][26][27][28], because the enthalpy formation of the binary Al-Ni is more negative and favors the formation of an Al-Ni intermetallic. The phase stability in alloys is governed by changes in the Gibbs free energy, given by:…”

Recent Advances in Additive Manufacturing of High Entropy Alloys and Their Nuclear and Wear-Resistant Applications

“…The effect of heat treatment on the wear behavior of Al 0.5 CoCrFeNi was studied by Gwalani et al [399]. They hot rolled (at 700 • C), annealed (at 1150 • C) and isothermally aged their alloy at 700 • C for 1, 4, 20, 40, 80 h. As the aging time increased, the B2 phase precipitated in the FCC matrix.…”