Neutron Studies of Order in Fe-Ni Alloys

Abstract

Neutron transmission measurements are used to study order in Fe-Ni alloys. The difference in neutron transmission between fully annealed and quenched alloys when plotted against the nickel content displays a broad peak around ${\mathrm{Ni}}_3$Fe and falls to vanishingly small values near 35 atomic percent Ni and pure Ni. The higher the degree of order the greater the neutron transmission. The substitution of 2.3 atomic percent Mo or 4.1 atomic percent Cr for Fe in the annealed 78 atomic percent Fe-Ni alloy caused a decrease in the neutron transmission, relative to the annealed 78 atomic percent Fe-Ni alloy, of 15.6 and 21.2 percent, respectively. The cold working of an annealed binary 75 atomic percent Ni alloy, a treatment known to produce disorder, gave rise to a decrease of 20.6 percent in neutron transmission. These results demonstrate that neutron techniques serve as a useful tool to study order in Fe-Ni alloys, and suggest that they can be extended to study other solid state phenomena.