Control mechanism of gadolinium-rich precipitates in new nuclear shielding FeCrNi alloys

Abstract

A series of different Ni content FeCrNi alloys incorporated with Gd was designed and fabricated. The gadolinium-rich precipitates in all alloys were identified through X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The types of precipitates transformed from M3Gd to M5Gd (M = Fe, Ni, Cr) intermetallic compound when the Ni content reached 30 wt.%. With increasing Ni content, the melting temperature of both the M3Gd and M5Gd phases improved. The melting temperature of M5Gd was more than 1200 °C, which was higher than the M3Gd precipitate, and this made alloys have narrow solidification temperature range. The structural stability of the gadolinium-rich precipitate and the interfacial strength calculated by density functional theory is discussed. These fabricated alloys with more than 30 wt.% Ni content also gave excellent shielding properties and deserve further investigation.