The Nature of the Microstructure and Interface Boundary Formation in Directionally Solidified Ceramic Boride Composites
Abstract
The goal of the project was to establish the interrelation between the phase interface condition, lattice mismatch of their crystal lattices, crystallographic orientation of the matrix phase relative to the direction of crystallization, thermal expansion coefficient mismatch between constituent phases of the composite, and structure formation processes together with the stress condition in directionally crystallized eutectic composites based on refractory boride compounds. It has been shown that co-orientation of crystal phases is independent from matrix orientation for LaB6-ZrB2 system. Ultrasonic and mechanical investigations have shown the influence of matrix orientation on composite modulus of elasticity. It has been shown that tensile strength of LaB6- ZrB2 DSE at 2000 deg C exceeds 200 MPa. It has been confirmed that the structural perfection is strongly influenced by the crystallographic orientation of the matrix. An abnormally low heat conductivity was measured for samarium hexaboride at temperatures higher than 1000 C. The influence of thermal coefficient mismatch on internal stress inside the matrix phase in SmB6 - (Ti,Zr)B2 system with varying Ti/Zr is comparable with precision of measurement. These findings can be extended to the related classes of eutectics, and the developed materials can serve as model objects for fundamental research in materials science.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2011
- Accession Number
- ADA546165
Entities
People
- Volodymyr B. Filipov
Organizations
- National Academy of Sciences