Corrosion Characteristics and Mechanical Properties of Zr-Sn-Nb Experimental Alloys

摘要

Two kinds of the specimens made of Zr-Sn-Nb experimental alloys were investigated for their corrosion behaviors and mechanical properties after some different thermo-mechanical treatments including the final heat treatments as stress-relived (SR) at 470 deg C and recrystallized (RX) at 520 deg C for 2.5 hours, respectively. The corrosion tests were carried out in the autoclaves containing 360 deg C water, 400 deg C steam and 360 deg C aqueous LiOH (70 ppm) solution. Microstructures of the tested specimens were analyzed using an optical microscopy and TEM, and those of their oxides using small angle XRD method. All of the tested specimens showed higher corrosion rates in the steam than in the water or the aqueous LiOH solution. The specimens having lower Nb and Sn content showed a little better corrosion resistance in all the environments than those having higher Nb and Sn content. It was found out that SR specimens had higher t-ZrO_2 fraction to m-ZrO_2 showing better corrosion resistance than that of RX ones as well as the SR ones had more hardness, tensile strength, and creep resistance than the RX ones.