Mt. Perrotsimonetta et A. Kobylanski, INFLUENCE OF TRACE-ELEMENTS ON HOT DUCTILITY OF AN ULTRA-HIGH PURITY INVAR ALLOY, Journal de physique. IV, 5(C7), 1995, pp. 323-334
Like steels, austenitic INVAR alloys Fe-Ni 36 % show a large ductility
trough between 500 degrees C and 1100 degrees C. To understand hot br
ittleness mechanisms and especially trace element effects, synthetic a
lloys were prepared using ultra-high purity iron and nickel doped with
selected amounts of carbon, sulphur, boron, aluminium, and nitrogen.
Four kinds of synthetic alloys were studied to establish the intrinsic
influence of sulphur, the combined effects of sulphur and precipitate
s such AlN or BN, and the effect of boron in the presence of sulphur,
on ductility and fracture mechanisms. We propose several mechanisms to
explain the loss and the recovery of ductility for each of the studie
d alloys, and then define the field of temperatures where these mechan
isms control ductility.