Tensile creep of fine grained (3–5 μm) Ti 3SiC 2 in the 1000–1200°C temperature range

Abstract

In this paper we report on the tensile creep behavior of fine-grained (3–5 μm) Ti 3SiC 2 in the 1000–1200°C temperature, T, range and the 10–100 MPa stress, σ, range. The creep behavior is characterized by three regimes a primary, quasi-steady state and a tertiary. In the quasi-steady state range and over the entire range of testing temperatures and stresses, the minimum creep rate, ε ̇ min , is given by: ε ̇ min ( s −1)= ε ̇ 0· exp[19±1]·(σ/σ 0) 1.5±0.1· exp (−445±10) kJ/mol RT where σ 0=MPa and ε ̇ 0=1 s −1. The times to failure, t f, were fitted to an expression of the form: t f (s)=t 0· exp[−2±1]·[ ε ̇ min / ε ̇ 0] −0.9±0.1 where t 0=1 s. Interrupted creep tests show that volume-conserving plastic deformation is the dominant source of strain during the secondary creep regime, while cavities and microcracks are responsible for the acceleration of the creep rate during the tertiary creep regime. Like in ice, large internal stresses, especially at high stresses, are developed in Ti 3SiC 2 during deformation, as a consequence of its extreme plastic anisotropy. The response of Ti 3SiC 2 to stress appears to be determined by a competition between the rates of accumulation and relaxation of these internal stresses.