TY - JOUR
T1 - Structural stability and thermal expansion of TiTaNbMoZr refractory high entropy alloy
AU - Behera, Madhusmita
AU - Panigrahi, Ajit
AU - Bönisch, Matthias
AU - Shankar, Gyan
AU - Mishra, Pratima Kumari
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/2/5
Y1 - 2022/2/5
N2 - A near-equiatomic TiTaNbMoZr refractory high entropy alloy (RHEA) was prepared by vacuum arc melting. It consists of two BCC solid solution phases (predominant and minor phase are named as B-major and B-minor, respectively) at room temperature. Structural stability and thermal expansion were investigated using in-situ synchrotron XRD and dilatometry. B-major phase is observed until 1273 K, whereas B-minor phase is present up to 1173 K. Above 1173 K, the formation of B′ phase is observed. The mean lattice coefficient of thermal expansion (αlm) and the mean dilatometric coefficient of thermal expansion (αdilm) are derived in the range of 323–1173 K and 323–1273 K, respectively. αlm increases linearly in the range of (8.1–8.8)× 10−6 K−1 and the mean αdilm varies from 7.5 × 10−6 K−1 to 10.9 × 10−6 K−1. Dilatometric strain and lattice strain are found to be identical up to 1000 K. However, beyond 1000 K, the dilatometric strain increases considerably in comparison to the lattice strain due to the generation of temperature-induced point defects (vacancies). The present work demonstrates that the TiTaNbMoZr RHEA exhibits structural (phase) stability up to 1173 K and thermal stability up to 1000 K.
AB - A near-equiatomic TiTaNbMoZr refractory high entropy alloy (RHEA) was prepared by vacuum arc melting. It consists of two BCC solid solution phases (predominant and minor phase are named as B-major and B-minor, respectively) at room temperature. Structural stability and thermal expansion were investigated using in-situ synchrotron XRD and dilatometry. B-major phase is observed until 1273 K, whereas B-minor phase is present up to 1173 K. Above 1173 K, the formation of B′ phase is observed. The mean lattice coefficient of thermal expansion (αlm) and the mean dilatometric coefficient of thermal expansion (αdilm) are derived in the range of 323–1173 K and 323–1273 K, respectively. αlm increases linearly in the range of (8.1–8.8)× 10−6 K−1 and the mean αdilm varies from 7.5 × 10−6 K−1 to 10.9 × 10−6 K−1. Dilatometric strain and lattice strain are found to be identical up to 1000 K. However, beyond 1000 K, the dilatometric strain increases considerably in comparison to the lattice strain due to the generation of temperature-induced point defects (vacancies). The present work demonstrates that the TiTaNbMoZr RHEA exhibits structural (phase) stability up to 1173 K and thermal stability up to 1000 K.
KW - Coefficient of thermal expansion
KW - Dilatometric strain
KW - Dilatometry
KW - High entropy alloy
KW - In-situ synchrotron XRD
KW - Point defects
UR - http://www.scopus.com/inward/record.url?scp=85115988429&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2021.162154
DO - 10.1016/j.jallcom.2021.162154
M3 - Article
AN - SCOPUS:85115988429
SN - 0925-8388
VL - 892
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 162154
ER -