Metallurgical Studies with the HIPPO Diffractometer at LANSCE

Advantages of neutron diffraction for metallurgical studies are highlighted with research examples performed on the High Pressure – Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron Science Center (LANSCE). We give a brief introduction of neutron diffraction and an overview of LANSCE. Neutrons offer unique advantages in particular for bulk microstructural characterization such as texture and phase composition. Therefore, the concept of neutron texture measurements will be introduced and its advantages discussed. As an example, we derive an explanation for observed texture memory effects during the α→γ→α transformation cycle in a 0.1%C-1%Mn hot-rolled steel sheet from the Kurdjumov-Sachs relationship. As an example for crystallographic studies of intermetallics, we describe how the previously inconclusive crystallographic structure of the Fe-Al ε phase, stable between 1095°C and 1231°C, was determined by in situ neutron diffraction to have the formula Fe₅Al₈ with a body-centered cubic structure of the Hume–Rothery Cu₅Zn₈ type at 1120°C.