Microstructure and mechanical properties of vacuum diffusion bonding joints for γ-TiAl based alloy

Abstract Vacuum diffusion bonding (DB) of as-extruded Ti-47.5Al-Cr-V (at.%) alloy was carried out at 1000–1100 °C at a pressure of 10–30 MPa for 1–3 h, and the bonded joints were post-bond heat treated (PBHT) at 1360 °C for 0.5 h. Subsequently, the shear strength of all the joints was measured, and the microstructure was observed. The results showed that the shear strength and bonding interface quality of joints increased under as-bonded and PBHT conditions with the increase of each bonding parameter (temperature, pressure, and time). The shear strength of the base material was 486 MPa, and it was 665 MPa after PBHT. Furthermore, the maximum shear strength of the as-bonded joints was over 80% of that of the base material. After PBHT, the maximum strength of the joints was nearly equal to that of the base material. The fracture morphologies of the as-bonded and PBHT joints were analyzed, and the fracture mode was changed from transgranular fracture to intergranular fracture. The optimal bonding parameters were proposed: T ≥ 1050 °C, p ≥ 20 MPa, and t ≥ 2 h.

[1]  C. Chen,et al.  Superplastic diffusion bonding of γ-TiAl-based alloy , 2004 .

[2]  Jian Cao,et al.  Interfacial microstructure and joining properties of TiAl/Ti3AlC2 diffusion bonded joints using Zr and Ni foils as interlayer , 2014 .

[3]  H. Clemens,et al.  Light-Weight Intermetallic Titanium Aluminides – Status of Research and Development , 2011 .

[4]  B. Liu,et al.  Diffusion bonding of Ti-45Al-7Nb-0.3W alloy by spark plasma sintering , 2016 .

[5]  Zhiwei Huang,et al.  Superplastic forming/diffusion bonding of laser surface melted TiAl intermetallic alloy , 2001 .

[6]  U. Kattner,et al.  Thermodynamic Assessment and Calculation of the Ti-Al System , 1992, Metallurgical and Materials Transactions A.

[7]  Xiaoguo Song,et al.  Diffusion bonding of TiAl intermetallic and Ti3AlC2 ceramic: Interfacial microstructure and joining properties , 2014 .

[8]  Hua-ming Wang,et al.  Microstructure and mechanical property of laser melting deposition (LMD) Ti/TiAl structural gradient material , 2010 .

[9]  M. Koçak,et al.  The fracture behavior of diffusion-bonded duplex gamma TiAl , 1996 .

[10]  R. Mehl.  Rates of Diffusion in Solid Alloys , 1937 .

[11]  Li Li,et al.  Effects of brazing temperature and testing temperature on the microstructure and shear strength of γ-TiAl joints , 2015 .

[12]  Manuel F. Vieira,et al.  Diffusion bonding of TiAl using reactive Ni/Al nanolayers and Ti and Ni foils , 2011 .

[13]  B. Derby,et al.  Theoretical model for diffusion bonding , 1982 .

[14]  T. V. Melnichenko,et al.  Diffusion welding of γ-TiAl based alloys through nano-layered foil of Ti/Al system , 2008 .

[15]  R. Shiue,et al.  Infrared brazing of Ti50Ni50 shape memory alloy using two Ag–Cu–Ti active braze alloys , 2006 .

[16]  H. Kestler,et al.  Phase stability of a γ-TiAl based alloy upon annealing: comparison between experiment and thermodynamic calculations , 2003 .

[17]  Chao Zhang,et al.  Bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy , 2015 .

[18]  L. Yajiang,et al.  Diffusion bonding of Fe-28Al(Cr) alloy with low-carbon steel in vacuum , 2006 .

[19]  U. E. Klotz,et al.  Diffusion bonding of gamma-TiAl using modified Ti/Al nanolayers , 2012 .

[20]  N. Moelans,et al.  Investigation of diffusion behavior in Cu–Sn solid state diffusion couples , 2016 .

[21]  X. P. Liu,et al.  Preparation of TiAl–Cr surface alloy by plasma-surface alloying technique , 2013 .

[22]  H. Clemens,et al.  Diffusion bonding of ?-TiAl sheets , 1999 .

[23]  J. Si,et al.  Simulation on extrusion process of TiAl alloy , 2011 .

[24]  Fritz Appel,et al.  Diffusion Bonding of γ(TiAl) Alloys: Influence of Composition, Microstructure, and Mechanical Properties , 2009 .

[25]  Ji-cai Feng,et al.  Brazing mechanism and infiltration strengthening of CC composites to TiAl alloys joint , 2010 .

[26]  J. Hawkyard,et al.  Solid state bonding in superplastic Ti-6Al-4V , 1984 .

[27]  Y. Mishin,et al.  Diffusion in the Ti–Al system , 2000 .

[28]  Minquan Zhang,et al.  Effect of Mo-alloyed layer on oxidation behavior of TiAl-based alloy , 2013 .