Over recent years,eutectic high-entropy alloys(EHEAs)have intrigued substantial research enthusiasms due to their good castability as well as balanced strength-ductility synergy.In this study,a bulk cast Al_(19.25)Co_...Over recent years,eutectic high-entropy alloys(EHEAs)have intrigued substantial research enthusiasms due to their good castability as well as balanced strength-ductility synergy.In this study,a bulk cast Al_(19.25)Co_(18.86)Fe_(18.36)Ni_(43.53)EHEA is developed with fine in-situ lamellar eutectics.The eutectics comprise alternating ordered face-centered-cubic(L1_(2))and ordered body-centered-cubic(B2)phases with semicoherent interfaces.The resulting microstructure resembles that of most reported as-cast EHEAs,but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition.Surprisingly,the B2 lamellae still feature much higher deformation resistance than the L1_(2) lamellae,so that less lattice defects are detected in the B2 lamellae until the fracture.More interestingly,in the L1_(2) lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension.The precipitate-free EHEA consequently shows excellent tensile ductility of~10%and high ultimate strength up to~956 MPa.展开更多
基金financial support from the National Key Research and Development Program of China(Nos.2018YFF0109404,2016YFB0300401 and 2016YFB0301401)the National Natural Science Foundation of China(Nos.U1732276 and U1860202)+4 种基金financial support from the National Natural Science Foundation of China(No.51704193)financial support from the National Natural Science Foundation of China(No.52004156)financial support from the National Natural Science Foundation of China(No.51904184)the supports from the National Science Foundation(DMR-1611180)the US Army Research Office(W911NF-19-2-0049)。
文摘Over recent years,eutectic high-entropy alloys(EHEAs)have intrigued substantial research enthusiasms due to their good castability as well as balanced strength-ductility synergy.In this study,a bulk cast Al_(19.25)Co_(18.86)Fe_(18.36)Ni_(43.53)EHEA is developed with fine in-situ lamellar eutectics.The eutectics comprise alternating ordered face-centered-cubic(L1_(2))and ordered body-centered-cubic(B2)phases with semicoherent interfaces.The resulting microstructure resembles that of most reported as-cast EHEAs,but the B2 lamellae are devoid of nano-precipitates because of the Cr-element removal in current tailored eutectic composition.Surprisingly,the B2 lamellae still feature much higher deformation resistance than the L1_(2) lamellae,so that less lattice defects are detected in the B2 lamellae until the fracture.More interestingly,in the L1_(2) lamellae we identify a dynamic microstructure refinement that correlates to extraordinary strain hardening in tension.The precipitate-free EHEA consequently shows excellent tensile ductility of~10%and high ultimate strength up to~956 MPa.
