Characterizing Micromechanical Properties of Friction Welding Interface between TiAl Alloy and GH3039 Superalloy.

Suigeng Du,Wanting Xu,Songlin Wang

doi:10.3390/ma13092072

Suigeng Du, Wanting Xu + Show 1 more

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https://doi.org/10.3390/ma13092072

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Abstract

To explore the macro-fracture mechanism of a friction welded joint between TiAl alloy and GH3039 superalloy, the micromechanical properties of intermediate phases at the joint interface are characterized and the relationship between the macro-fracture and micro-fracture of the joint is established. The indentation technique has been employed to calculate the nano-hardness and fracture toughness of the intermediate phases. The dynamic in-situ tensile test in SEM has been applied to observe the initiation and propagation process of cracks at the interface. It has been found that Al3NiTi2 and AlNi2Ti have the highest nano-hardness and elastic recovery rates, while TiAl and GH3039 base metals have the lowest nano-hardness and elastic recovery rates. This indicates that the harder the materials, the more prone they are to elastic deformation. Nevertheless, the fracture toughness of Al3NiTi2 and AlNi2Ti are the two lowest, which were 1.7 MPa·m1/2 and 2.7 MPa·m1/2, respectively. The cracks sprouted from Al3NiTi2 and AlNi2Ti and then spread throughout the entire intermediate phase zone. In other words, the fracture mainly happened in these two phase layers. It has been concluded that Al3NiTi2 and AlNi2Ti were the two weakest phases at the interface and their poor fracture toughness results in low joint strength.

Highlights

TiAl-based alloys, as promising, high-temperature structural materials, have been widely used in aero-engine components due to their excellent features, such as low density, high specific strength, favorable oxidation resistance and high-temperature mechanical properties [1,2]
GH3039were were characterized by nano-hardness, fracture toughness and in-situ tensile
The main conclusions are characterized by nano-hardness, fracture toughness and in-situ tensile

Summary

Introduction

TiAl-based alloys, as promising, high-temperature structural materials, have been widely used in aero-engine components due to their excellent features, such as low density, high specific strength, favorable oxidation resistance and high-temperature mechanical properties [1,2]. The turbine rotor of a turbocharger made by TiAl alloy can be lightened more than 50% compared with that made by a Ni-based casting superalloy [3]. GH3039 superalloy has been adopted as the interlayer to effectively implement the friction welding of TiAl to 42CrMo steel in a previous study [7]. To explore the macro-fracture mechanism and enhance the strength of the TiAl/GH3039 friction welded joint, it is necessary to characterize the micromechanical properties of the interface and establish the relationship between the macro-fracture and micro-fracture of the joint

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Discussion

Conclusion