The effe
ct of small additions of boron and
carbon on the environment embrittlement at different temperature of Ni–19Si–3Nb based alloy was investigated by atmosphere-
controlled tensile test in various
conditions. The results revealed that the Ni–19Si–3Nb base alloy exhibits du
ctile me
chani
cal behavior (UTS
center border=0 SRC=/images/glyphs/BQ1.GIF>1250 MPa,
?center border=0 SRC=/images/glyphs/BQ1.GIF>14%) at room temperature in va
cuum (2×10
−4torr) as well as in pure oxygen atmosphere. This indi
cates that environmental embrittlement due to water vapor is the major fa
ctor to the deterioration of the du
ctility of Ni–19Si–3Nb base alloy. In parallel, 300 ppm boron addition signifi
cantly improves the ultimate tensile strength and the du
ctility (UTS≥1200 MPa,
?≥12%) in the Ni–19Si–3Nb base alloy at room temperature in various atmosphere of pure oxygen, air (
contains 14000 ppm water vapor), and pure water vapor (
contains 850 ppm water vapor). In addition, the yield strength of the Ni–19Si–3Nb–0.15B–0.1C alloy in
creases with temperature, and the maximum yield strength o
ccurs at 873 K. However, the du
ctility of the Ni–19Si–3Nb–0.15B–0.1C alloy drops signifi
cantly when the temperature in
creases to 973 K.