Microstructural Evolution and Mechanical Properties of Graphene Oxide-Reinforced Ti6Al4V Matrix Composite Fabricated Using Spark Plasma Sintering.

Ying Song,Weiwei Liu,Yao Chen,Shaokang Guan,Yufeng Sun

doi:10.3390/nano11061440

Abstract

To achieve a further reduction in weight of titanium alloys and to satisfy the increasing demand of energy-saving for aerospace and automotive applications, a graphene oxide nanosheet-reinforced Ti6Al4V (GO/TC4) composite was successfully fabricated using spark plasma sintering (SPS). Contrary to the Widmanstätten microstructure of a monolithic TC4 sample, the microstructure of the composites displayed a typical basket-weave structure in virtue of the introduced residual tensile stress generated from the mismatch of coefficients of thermal expansion (CTE) between GO and TC4 during the phase transformation. Meanwhile, the in situ-formed TiC nanolayer and diffusion layer were identified at the GO–TC4 interface, which is expected to endow a stronger interfacial bonding. As compared with the TC4 sample, the TC4 composite with the addition of 0.27 wt.% GO exhibited a 0.2% yield strength of 921.8 MPa, an ultimate tensile strength of 1040.1 MPa, and an elongation of 5.3%, displaying a better balance of strength and ductility than that of the composite with a higher GO addition (0.54 wt.%). The synergetic strengthening mechanisms such as Orowan strengthening, enhanced dislocation density strengthening, and load transfer were confirmed. Among them, load transfer contributed greatly to the strength of the composites due to improved interfacial bonding between the GO fillers and TC4 matrix.

Highlights

Titanium alloys have been widely recognized as important and promising engineering materials used in diverse industrial fields spanning aerospace, weaponry, automobiles, biomedicine, and others, because they exhibit a good combination of low density [1], high specific strength [2], excellent corrosion resistance [1], and biocompatibility [3]
As improved strength associated with the addition of graphene oxide (GO) in the composites was achieved bycompared to the results reported in previous investigations, the 0.25 wt.% graphene/TC4 composite compromising their elongation to failure, especially for the 0.54GO/TC4 sample, sharply fabricated using spark plasma sintering (SPS) at high pressures (250 MPa) displayed a yield strength (YS) of ~964 MPa and ultimate tensile strength (UTS) of decreasing to ~1.8%
Composite waswas successgrapheneoxide oxidenanosheet-reinforced nanosheet-reinforced composite successfully fabricated using spark plasma sintering (SPS), in which the electrostatic self-assembly fully fabricated using spark plasma sintering (SPS), in which the electrostatic self-assembly method was employed to homogeneously disperse GO in the TC4 powders

Summary

Introduction

Titanium alloys have been widely recognized as important and promising engineering materials used in diverse industrial fields spanning aerospace, weaponry, automobiles, biomedicine, and others, because they exhibit a good combination of low density [1], high specific strength [2], excellent corrosion resistance [1], and biocompatibility [3]. Among these titanium alloys with different compositions, the Ti6Al4V alloy is dominant in the aerospace market, making up about 60% of the titanium used in jet engines and up to. As compared to the well-known one-dimensional carbon nanotube (CNT), selecting graphene as a reinforcement has the following advantages: (1) graphene is much more cost-effective than CNT and can be produced on a large scale; (2) graphene with a higher surface area is prone to form stronger interfacial bonding with a metal matrix

Methods

Results

Conclusion