Ag-decorated-GO 2D-film as a promising strategy for inhibiting the cross-interface diffusion and reconfiguration of Ag-GO@MoAlB/CMCs

To inhibit the interfacial decomposition of MoAlB in Cu-matrix composites, an Ag-decorated graphene oxide (Ag-GO) shell was assembled on MoAlB particles to construct a core-shell-like precursor for interfacial regulation. During hot pressing, the Ag-GO shell effectively suppressed outward diffusion of Al, with image analysis of the EDS maps showing that approximately 78.77% of the Al-related area was retained within the reinforcement-particle region. As a result, the interface changed from a decomposition-derived MoB/Al₂O₃/Cu structure to a modified assemblage containing retained MoAlB, MoB, Ag, Ag₃Al, and Al₂O₃. Raman spectroscopy further confirms that an Ag-GO-derived carbonaceous interphase remains detectable after hot pressing. HRTEM and GPA analyses reveal that the MoAlB to β-MoB transformation proceeds through a gradual defect-assisted crystallographic conversion driven by continuous Al depletion, rather than abrupt phase replacement. First-principles calculations further show that the Al-terminated MoAlB/Cu interface has the weakest interfacial bonding, whereas Al becomes more stable after entering the Cu side, providing an energetic explanation for outward Al diffusion and interfacial reconstruction. In addition, Ag-GO modification improved the electrical conductivity to ∼57% IACS, increased the compressive strength to ∼790 MPa and the compressive strain to ∼21%, while reducing the reaction-induced hardening of the Cu matrix. These results demonstrate that the Ag-GO shell acts as an effective reaction-regulating interphase for stabilizing MoAlB in Cu-based composites.