Thermal Properties of (Zr, TM)B₂ Solid Solutions with TM = Ta, Mo, Re, V, and Cr

Abstract

The thermal propertieswere investigated for hot-pressed zirconium diboride containing solid solution additions of tantalum, molybdenum, rhenium, vanadium, and chromium. Thenominal additions were equivalent to 3 at.% of each metal with respect to zirconium. Using 0.5 wt% carbon as a sintering aid, powders were hot-pressed to near full density at 2150C. Rietveld refinement of X-ray diffraction data was used to measure lattice parameters and to ensure that the additives formed solid solutions. Thermal conductivities were calculated from measured thermal diffusivities and temperature-dependent values for density and heat capacity. Thermal conductivities at 25⁰C ranged from 88 W·(m·K)-1 for nominally pure ZrB2 down to 28 W·(m·K)-1 for (Zr,Cr)B2. Electron contributions to thermal conductivity were calculated from electrical resistivity measurements using theWiedemann-Franz law. Decreases in phonon and electron conduction correlated with thesize ofthemetallic additive, indicating that changes in atom size in theZr lattice positions reduced thermal transport.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Additives; Rietveld refinement; Sintering; Solid solutions; Specific heat; Thermodynamic properties; X ray diffraction; Zirconium; Electrical resistivity measurements; Electron conduction; Metallic additives; Temperature dependent; Thermal transport; Wiedemann-Franz law

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 Blackwell Publishing Inc., All rights reserved.

Publication Date

01 Dec 2014

Link to Full Text

Share

 
COinS