Tailoring strength-ductility of titanium matrix composites reinforced with graphene nanoplatelets

In this study, graphene nanoplatelets reinforced titanium matrix (GNPs/CT20) composites with adjustable performance were fabricated via 3D vibration milling and spark plasma sintering. With the progressive increase of GNPs, a quasi-continuous 3D reinforcement (TiC-GNPs-TiC) network was established and a peculiar phenomenon is observed that the ductility of GNPs/CT20 composites trends in hump type while the strength increases monotonically. The first crest of the humping ductility for GNPs/CT20 composites was attributed to the fine-grained CT20 matrix contributed by GNPs and in-situ generated TiC. Subsequently, the increasing TiC with discrete distribution dominated the tensile ductility behaviour which showed as the valley of humping ductility. Further additions of GNPs led to the network distribution of TiC-GNPs-TiC, which contributed to a relatively uniform deformation and the near equiaxed fine-grained microstructure gradually replacing the original Widmanst atten microstructure, thus promoting the second crest of the humping ductility. Finally, lots of TiC-GNPsTiC further improved strength but inevitably reduced ductility for their serious agglomeration. This study focuses on the strengthening and toughening mechanisms of the quasi-continuous 3D TiC-GNPs-TiC network in titanium matrix reinforced by GNPs (TMCGs) and provides new insights into the design and fabrication of TMCGs with excellent strength-ductility.

Automated summary

In this study, graphene nanoplatelets reinforced titanium matrix composites were fabricated and their properties were adjusted through the addition of graphene nanoplatelets. The addition of graphene nanoplatelets resulted in a peculiar trend in which the ductility of the composites showed a hump type behavior while the strength increased monotonically. The humping ductility was attributed to the fine-grained matrix contributed by graphene nanoplatelets and in-situ generated titanium carbide. Further additions of graphene nanoplatelets led to the establishment of a network distribution of titanium carbide and graphene nanoplatelets, which resulted in a more uniform deformation and the formation of a near equiaxed fine-grained microstructure. However, excessive additions of titanium carbide and graphene nanoplatelets improved the strength but reduced the ductility due to their agglomeration.