Creep properties of Zr-based alloys with Zr-xNb-xSn-Fe-Cr-Mn alloying system

To investigate the effect of Nb and Sn on the mechanical properties of Zr-based alloys with Zr-xNb-xSn-Fe-Cr-Mn alloying system, the Zr-based alloys were manufactured as two kinds of sheet specimens and tested for tensile properties and creep behaviors. PK2 alloy, which have more Sn content than Nb, showed higher tensile strength and creep resistance than PK1 alloy. With rising the applied stress and test temperature, PK1 and PK2 alloys increased the steady state creep rate and activation energy for the creep of the alloys. This behavior would be due to the effect of solid-solution hardening of Sn and the dislocation in worked structure. The stress exponent of the alloys also increased in response to rise the applied stress at the constant temperature. In the stress range of 50 to 180 MPa at 350 .deg. C and 400 .deg. C, the alloys showed creep deformation behavior due to diffusion and viscous dislocation glide mechanism below 4 of the stress exponent (n). Based on the higher stress exponent than 7. It is thought that the alloys were strained by dislocation climb mechanism at the applied stress over 100 MPa at 450 .deg. C