A novel (B4Cp+Gd)/Al6061 neutron absorber material with desirable mechanical properties

Abstract

A novel (10 wt%B4Cp+3.6 wt%Gd)/Al6061 neutron absorber material having great potential commercial applications was designed by calculating equivalent B content (BEq) and its neutron absorber ability was evaluated based on an equivalent B areal density (EBAD) calculation as well as a Monte Carlo simulation. The designed material was successfully fabricated by ultrasound assisted casting method. The added B4C particles were distributed uniformly in the matrix and the newly formed large-sized Al3Gd particles existed along the grain boundaries (GBs) in the as-cast composite. It was found that a small amount of Si was solubilized in Al3Gd lattice and the solution behavior of Si was revealed using first-principles calculation. After hot extrusion (HE) and heat treatment (HT), the large-sized Al3Gd particles were broken into small ones and nano-sized βʺ phase was precipitated in the matrix. The mechanical properties of the modified composite were enhanced remarkably and the reason of which was mainly attributed to the following two aspects. On the one hand, HE induced the grain refinement and the fragmentation of large-sized Al3Gd particles as well as their more homogeneous distribution within grains from GBs were beneficial for the improvements in both strength and ductility of composite. On the other hand, HT induced the precipitation of βʺ phase could work as strengthening phase in the modified composite. The size and distribution of Al3Gd particles played an important role in improving the mechanical properties since cracking easily occurred on the large-sized Al3Gd particles which existed along GBs, leading to the severe degradation of mechanical properties of the as-cast composite. Furthermore, the related mechanism of cracking behavior of large-sized Al3Gd particles was discussed. This research provides a low-cost method to prepare easy-deform Al based neutron absorber material with desirable mechanical properties.