Citation

Ström E, Eriksson S, Rundlöf H, Zhang J. Acta Materialia 2005; 53(2): 357-365.

Copyright

(Copyright © 2005)

DOI

10.1016/j.actamat.2004.09.031

PMID

unavailable

Abstract

The fundamental thermophysical properties of Mo5Si3 have been investigated. The pronounced mismatch in the coefficient of thermal expansion (CTE) between the c- and a-directions of monolithic Mo 5Si3 was reduced significantly by alloying additions. 25 at.% Cr reduced the CTE-mismatch to 1.45 in Mo3Cr2Si 3, while 25 at.% Ti resulted in a mismatch of 1.32. Rietveld refinement of neutron powder diffraction data of the studied compounds reveals that Cr, having a smaller radius than Mo, has preference for the 4b chain sites of the D8m unit cell of Mo5Si3. In contrast, Ti atoms, being larger than Mo, occupy almost entirely the 16k sites in the unit cell interior. Compression tests of cast Mo5Si3 at 1573 K indicate that 25% Ti or Nb additions both result in brittle fracture, whereas Mo5Si3 containing 25% Cr deforms plastically. 25% Cr additions decreases the yield strength to approximately half of that of monolithic Mo5Si3 at 1573 K. © 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Language: en

Keywords

Silicon; Scanning electron microscopy; Alloying; Doping (additives); Energy dispersive spectroscopy; Reduction; Phase transitions; Transition metal suicides; Crystal structure; Ternary systems; X ray powder diffraction; Neutron diffraction; Plastic deformation; Molybdenum alloys; Thermal expansion; Brittle fracture; Brittle-to-ductile transition; Coefficient of thermal expansion (CTE); High temperature deformation; High temperature operations; Neodymium; Transition metal silicides