Formation of Stacking Fault Tetrahedra and Diffuse Streaks along 〈111〉 in the Equiatomic Cr-Co-Ni Medium-Entropy Alloy

• Published in: MATERIALS TRANSACTIONS Vol. 65; no. 9; pp. 1049 - 1054
• Main Authors: Li, Le, Chen, Zhenghao, Kishida, Kyosuke, Inui, Haruyuki
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals and Materials 01.09.2024; Japan Science and Technology Agency
• Subjects: diffuse streaks; Heat resistant alloys; Heat treatment; High temperature; high-entropy alloys; Ion irradiation; Medium entropy alloys; quenching; Specimen preparation; stacking fault tetrahedra; Stacking faults; Tetrahedra; vacancy formation and migration
• ISSN: 1345-9678; 1347-5320
• DOI: 10.2320/matertrans.MT-MA2024001

Formation of stacking fault tetrahedra and diffuse streaks along 〈111〉 in the equiatomic Cr-Co-Ni medium-entropy alloy subjected to different heat-treatments and different specimen preparation methods are examined by transmission electron microscopy. Neither stacking faults nor stacking fault tetrahedra are formed simply by quenching from a high temperature due to the high energy barrier for the formation and migration of vacancies. These defects, however, are found to form by Ar+-ion irradiation, as abundant vacancies are continuously introduced during ion-irradiation so as to bypass the high energy barrier for the formation. Diffuse streaks along 〈111〉 are usually observed in the SAED pattern with the 〈110〉 incidence regardless of heat-treatments and specimen preparation methods, indicating the occurrence of diffuse streaks is nothing to do with the formation of stacking faults and stacking fault tetrahedra.