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Comprehensive analysis of ordering in CoCrNi and CrNi 2 alloys.

Vinícius P BacurauPedro Augusto Franco Pinheiro MoreiraGustavo BertoliAngelo F AndreoliEric MazzerFlávio F de AssisPiter GargarellaGuilherme KogaGuilherme C StumpfSantiago José Alejandro FigueroaMichael WidomMichael KaufmanAndrea FantinYifan CaoRodrigo FreitasDaniel MiracleFrancisco Gil Coury
Published in: Nature communications (2024)
Chemical Short-Range Order (CSRO) has attracted recent attention from many researchers, creating intense debates about its impact on material properties. The challenges lie in confirming and quantifying CSRO, as its detection proves exceptionally demanding, contributing to conflicting data in the literature regarding its true effects on mechanical properties. Our work uses high-precision calorimetric data to unambiguously prove the existence and, coupled with atomistic simulations, quantify the type of CSRO. This methodology allows us to propose a mechanism for its formation and destruction based on the heat evolution during thermal analysis and facilitates a precise identification of local ordering in CoCrNi alloys. Samples of CoCrNi (Co 33 Cr 33 Ni 33 ) and CrNi 2 (Cr 33 Ni 66 ) alloys are fabricated in varying ordered states, extensively characterized via synchrotron X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. Samples with considerably different ordered states are submitted to tensile tests with in-situ synchrotron X-ray diffraction. We demonstrate, despite inducing varied CSRO levels in CoCrNi, no significant alterations in overall mechanical behavior emerge. However, the CrNi 2 alloy, which undergoes long-range ordering, experiences significant shifts in yield strength, ultimate tensile stress and ductility.
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