Control of nanoscale precipitation and elimination of intermediate-temperature embrittlement in multicomponent high-entropy alloys

Microstructures and Mechanical Properties of As Cast (Al7.5Co21.9Cr10.9Ti5.0Fe21.9Ni32.8)100-xCux High-Entropy Alloys

“…All three HEAs break suddenly at the stage of stress rise. According to previous studies (He et al, 2016;Yang et al, 2020), the increased coherent interface in ID often improves the tensile strength, and the fine dispersion precipitation usually improves the ductility. Therefore, the observed decrease in tensile strength and elongation indicates that the fracture is most likely to originate from the DR region rather than the ID.…”

The Evolution of Intermetallic Compounds in High-Entropy Alloys: From the Secondary Phase to the Main Phase

“…The presence of a small number of precipitation phases will not cause much damage to the ambient-temperature performance of the material. However, it will cause severe grain boundary embrittlement of the alloy at the intermediate temperature (usually about 600-800 • C), which is the so-called intermediate-temperature embrittlement [126,127]. To address this issue, Yang et al [128] obtained the solidification path of the intergranular heterogeneous precipitation phase by analyzing the evolution of the solidification structure at the grain boundary during the aging process, and thus proposed a duplex-aging strategy, as shown in Figure 13.…”

“…To date, many studies have demonstrated that most HEIs have excellent strengthplasticity synergies over a wide temperature range of 77 to 293 K [73,85,127,160]. Based on the excellent properties of HEIs, researchers have also explored the deformation methods of this new material.…”

Development and characterisation of new high entropy alloy systems of dual and/or multiple phases

“…The lowering of grain boundary energy through the formation of these precipitates, attenuates the driving force for grain growth and as such the 160h aged alloy exhibits a more refined grain morphology. Cellular precipitates along the grain boundaries are also reported in similar FCC+L12 microstructures [292,294,301,305,328].…”

“…It is reported that the increased supersaturation of Ti and Al near the grain boundaries' territory thermodynamically destabilizes the L12 structure and a more stable ordered BCC-type Heusler phase is formed at the grain boundaries [328]. Moreover, Yang et al [328,329] when investigating two alloy compositions of the Fe-Co-Ni-Al-Ti system with small amounts of Ti and Al (up to 8 at.%) and with aging temperature at 800 °C (pretty close to the selected aging temperature in our case: 750 °C), claimed that Ti additions greater than the range of 6.5 to 7.5 at.%, will promote the formation of more brittle L21 particles (without however mentioning the Heusler characterization). A schematic representation of the formation sequence of this certain type of precipitates is illustrated in Figure 11.8.…”