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Mechanical Properties of Metallic Perovskite Mn 3 Cu 0.5 Ge 0.5 N:High‐Stiffness Isotropic Negative Thermal Expansion Material
Author(s) -
Nakamura Yoshinobu,
Takenaka Koshi,
Kishimoto Akira,
Takagi Hidenori
Publication year - 2009
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/j.1551-2916.2009.03297.x
Subject(s) - thermal expansion , negative thermal expansion , materials science , antiperovskite , intermetallic , isotropy , bulk modulus , perovskite (structure) , composite material , nitride , elastic modulus , doping , crystallography , chemistry , layer (electronics) , physics , optoelectronics , alloy , quantum mechanics
The basic mechanical properties of antiperovskite manganese nitride, Mn 3 Cu 1− x Ge x N, known as an isotropic negative thermal expansion (NTE), have been evaluated. The mother material, Mn 3 CuN, was a soft and ductile intermetallic compound with a positive linear thermal expansion coefficient (α=+20 × 10 −6 K −1 ) at room temperature. The thermal expansion properties of Mn 3 CuN were dramatically changed by Ge doping, resulting in an extremely large NTE material (α=−12.5 × 10 −6 K −1 ) by 50% substitution of Cu with Ge. Associate with this, the mechanical properties were found to be strongly modified by Ge doping, and both the stiffness and the hardness of Mn 3 Cu 1− x Ge x N increased with increasing the Ge content, x . The NTE material, Mn 3 Cu 0.5 Ge 0.5 N, had an enhanced hardness of 570–620 H v and an exceptionally large Young's modulus of 211–320 GPa. The giant, isotropic NTE compatible with the enhanced value of Young's modulus enables us to fabricate extremely stiff, stable, and lightweight zero thermal expansion composites for the use in many fields of industries.