Thermal expansion of the V5Si3 and T-2 phases of the V-Si-B system investigated by high-temperature X-ray diffraction

Author(s)

Rodrigues, Geovani ^[1] ; Nunes, Carlos Angelo ^[2] ; Suzuki, Paulo Atsushi ^[2] ; Coelho, Gilberto Carvalho ^[2]

Affiliation

^[1] UniFoa Ctr Univ Volta Redonda, BR-27240560 Rio De Janeiro - Brazil

^[2] Univ Sao Paulo, EEL, BR-12602810 Lorena, SP - Brazil

• Document type: Journal article
• Source: INTERMETALLICS; v. 17, n. 10, p. 792-795, OCT 2009.
• Web of Science Citations: 8

Abstract

The thermal expansion anisotropy of the V(5)Si(3) and T(2)-phase of the V-Si-B system were determined by high-temperature X-ray diffraction from 298 to 1273 K. Alloys with nominal compositions V(62.5)Si(37.5) (V5Si3 phase) and V(63)Si(12)B(25) (T(2)-phase) were prepared from high-purity materials through arc-melting followed by heat-treatment at 1873 K by 24 h, under argon atmosphere. The V(5)Si(3) phase exhibits thermal expansion anisotropy equals to 1.3, with thermal expansion coefficients along the a and c-axis equal to 9.3 x 10(-6) K(-1) and 11.7 x 10(-6) K(-1), respectively. Similarly, the thermal expansion anisotropy value of the T(2)-phase is 0.9 with thermal expansion coefficients equal to 8.8 x 10(-6) K(-1) and 8.3 x 10(-6) K(-1) along the, a and c-axis respectively. Compared to other isostructural silicides of the 5:3 type and the Ti(5)Si(3) phase, the V(5)Si(3) phase presents lower thermal expansion anisotropy. The T(2)-phase present in the V-Si-B system exhibits low thermal expansion anisotropy, as the T(2)-phase of the Mo-Si-B, Nb-Si-B and W-Si-B systems. (C) 2009 Elsevier Ltd. All rights reserved. (AU)