Effects of environment and temperature on the mechanical behavior of the Ni–19Si–3Nb–0.15B based intermetallic alloy with chromium addition

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The effect of chromium addition to the Ni–19Si–3Nb–0.15B based alloy on the environment embrittlement at different temperature was investigated by the atmosphere-controlled tensile test in various conditions. Our experimental result reveals that the addition of chromium results in destabilizing the β phase (Ni 3Si) and forming the hard Ni 5Si 2 plate phase. These hard Ni 5Si 2 plates play a major role of ductility deterioration of those alloys in this study. The elongation tested in vacuum, air and water vapor for the Ni–18Si–3Nb–0.15B–1Cr alloy exhibits a significantly increase with temperature from 973 to 1073 K. In addition, fracture surfaces tested at 1073 K in vacuum, water vapor, and air atmosphere present a typical ductile fracture surface, a fully dimpled fracture pattern. This observation appears to be well correlated with those results of tensile elongation and indicates that the addition of chromium may suppress the environmental embrittlement at high temperature (i.e. 1073 K).