Fabrication, microstructure, and mechanical properties of a novel GdB2C2/ 6061Al composites with outstanding thermal neutron shielding properties

This study successfully fabricated a new type of composites, GdB2C2/6061Al, with outstanding thermal neutron shielding properties. This was achieved for the first time using a combination of vacuum hot-press sintering and hot rolling techniques. The macroscopic thermal neutron absorption cross section of 3 vol% GdB2C2/6061Al composites (28.72 cm−1) was comparable to that of 32 vol% B4C/Al composites (26.88 cm−1). A theoretical thermal neutron transmittance of 1×10−4 was achieved by incorporation of 3 vol% GdB2C2 into a 6061 Al matrix at a thickness of 0.32 cm. For the 3 vol% GdB2C2/6061Al composites, the as-sintered specimens demonstrated a yield strength (YS) of 70 MPa, an ultimate tensile strength (UTS) of 157 MPa, and an elongation (EL) of 9.36 %. Following rolling, the YS and UTS increased to 135 MPa and 185 MPa, respectively, while the ELdecreased to 5.33%. The primary strengthening mechanism in as-rolled GdB2C2/6061Al composites was thermal mismatch strengthening, followed by load transfer strengthening. Grain refinement had the least contribution to the YS of the composites. In addition, the dislocation pinning effect caused by in-situ formed Al4C3 and MgO at the GdB2C2/6061Al interface also played a significant role. This study provides new insights into the development of advanced thermal neutron shielding materials, particularly for applications in spent nuclear fuel storage and transportation.