Joining of TiAl to Steel by Diffusion Bonding with Ni-Ti Reactive MultilayersReport as inadecuate




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CEMUC, Department of Metallurgical and Materials Engineering, University of Porto, R. Dr. Roberto Frias, Porto 4200-465, Portugal

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CEMUC, Department of Mechanical Engineering, University of Coimbra, R. Luís Reis Santos, Coimbra 3030-788, Portugal





*

Author to whom correspondence should be addressed.



Academic Editor: Hugo F. Lopez

Abstract Dissimilar diffusion bonds of TiAl alloy to AISI 310 stainless steel using Ni-Ti reactive multilayers were studied in this investigation. The Ni and Ti alternating layers were deposited by d.c. magnetron sputtering onto the base materials, with a bilayer thickness of 30 and 60 nm. Joining experiments were performed at 700 and 800 °C for 60 min under pressures of 50 and 10 MPa. The effectiveness of using Ni-Ti multilayers to improve the bonding process was assessed by microstructural characterization of the interface and by mechanical tests. Diffusion bonded joints were characterized by scanning electron microscopy SEM, energy dispersive X-ray spectroscopy EDS, electron backscatter diffraction EBSD, transmission electron microscopy TEM and selected area electron diffraction SAED, high resolution TEM HRTEM and Fast Fourier transform FFT. The bonding interfaces are thin approximately 5 µm thick with a layered microstructure. For all joints, the interface is mainly composed of equiaxed grains of NiTi and NiTi2. The thickness and number of layers depends on the joining conditions and bilayer thickness of the multilayers. Mechanical characterization of the joints was performed by nanoindentation and shear tests. Youngs modulus distribution maps highlight the phase differences across the joints interface. The highest shear strength value is obtained for the joint produced at 800 °C for 60 min under a pressure of 10 MPa using Ni-Ti multilayers with 30 nm of bilayer thickness. View Full-Text

Keywords: diffusion bonding; TiAl; stainless steel; multilayers diffusion bonding; TiAl; stainless steel; multilayers





Author: Sónia Simões 1, Ana S. Ramos 2, Filomena Viana 1, Maria Teresa Vieira 2 and Manuel F. Vieira 1,*

Source: http://mdpi.com/



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