High temperature creep resistance of a thermally stable nanocrystalline Fe-5 at.% Zr steel

The application of nanocrystalline (NC) materials at high temperatures is challenging due to their poor thermal stability or low creep resistance. Here we report that a thermally stable NC Fe-5 at.% Zr steel produced by High-Pressure-Thermal-Compression sintering exhibits an excellent creep resistance (with a creep rate of 3.92 × 10−8 s−1 at 923 K and under the applied stress of 250 MPa). The excellent creep resistance is ascribed to its highly stable NC structure stabilized by nano-sized precipitates. Mechanical testing suggests that the creep of the NC Fe-5 at.% Zr steel is controlled by dislocation activities rather than diffusion dominated mechanisms.