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M 2 YSi (M=Rh, Ir): Theoretically predicted damage‐tolerant MAX phase‐like layered silicides
Author(s) -
Zhou Yanchun,
Xiang Huimin,
Dai Fuzhi,
Feng Zhihai
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15186
Subject(s) - materials science , shear modulus , yttrium , phase (matter) , composite material , crystallography , nanotechnology , chemistry , oxide , metallurgy , organic chemistry
Abstract Searching for layered MAX phase‐like materials with properties of both ceramics and metals is a topic in its infancy. Herein, through a combination of crystal structure, electronic structure, chemical bonding, and elastic property investigations, we report two MAX phase‐like layered materials Rh 2 YSi and Ir 2 YSi. Rh 2 YSi and Ir 2 YSi have bulk modulus B of 150 and 185 GPa, respectively, which are comparable to the typical MAX phases like Ti 2 AlC, Ti 3 AlC 2 , and Ti 3 SiC 2 , but much lower shear modulus G (82 and 97 GPa for Rh 2 YSi and Ir 2 YSi, respectively) than MAX phases. The high stiffness is due to the presence of rigid Si2–M–Si3–M (M = Ir, Rh) units, while the low shear deformation resistance is due to the presence of metallic bonds and the weak bonds that link the rigid Si2–M–Si3–M (M = Ir, Rh) units. Based on the low shear deformation resistance and low Pugh's ratio, Rh 2 YSi and Ir 2 YSi are predicted as damage‐tolerant silicides and promising water vapor‐resistant interphase materials for SiC f /SiC composites if yttria or yttrium silicates are formed to protect the SiC fibers in oxygen containing environments. The possible slip systems are {0001} < 2 1 ¯1 ¯ 0 > and { 11 2 ¯ 0 } <0001> for both Rh 2 YSi and Ir 2 YSi.