Research On Brazing Process Of TiAl-Ni Heterogenous Materials

In the future,titanium aluminum alloys have great potential in the application of aerospace high temperature lightweight structural materials,and achieving their connection with traditional nickel based superalloys is significant.However,it is difficult to connect the two materials because of difference between them.Brazing is an effective means to connect dissimilar materials,but its joint strength and heat resistance are poor.So it is significant to make brazing filler metal and TiAl-Ni dissimilar materials connecting,which has the practical application of TiAl alloy.In this paper,the research objecsts are nickel based superalloy GH536 and Ti48Al2Nb2Cr(at%)aluminum alloy titanium dissimilar materials,the amorphous solder for braze middle layer to achieve the TiAl-Ni heterogeneous component connection.The properties of joints such as microstructure,composition and mechanical were analyzed,We also explore the mechanism of brazing of TiA-Ni dissimilar materials.The main results are as follows:(1)The TiZrBeCo amorphous solders with thickness and width of 40?60 and 5?15 mm are prepared by melt-spinning system.The surface of the foil has no defects,and toughness and corrosion resistance are good;(2)Ti35Zr25Be30Co10 amorphous solder has a good wettability with nickel based superalloy and titanium aluminum alloy material,And with the increase of temperature and holding time,the wettability of solder are enhenced.At 900?,when the holding time is 10 min,the contact angle of GH536-Ti35Zr25Be30Co10 and TiAl-Ti35Zr25Be30Co10 can reach 18.6 and 14.1°,separately;(3)When the holding time is 30 minwith temperature of 800?,850? and 900?,the room temperature shear strength of TiAl-Ni heterogeneity joint with the rising of brazing temperature from increasing to decreasing;At 850 ?,the room temperature shear performance of joints because the holding time increases;(4)During the brazing process,new phase is formed with Ti35Zr25Be30Co 10 amorphous solder and titanium aluminum alloy and nickel base superalloy interacting.The key is to generate new phase.The reaction diffusion behavior of new phase is the key to obtain good performance of the heterojunction;(5)The interface structure of GH536-TiZrBeCo-TiAl is:(Ni-Fe-Cr)solid solution/rich Ti(Ni-Cr-Fe)solid solution/TiZrBe eutectic structure containing Ti2Ni and NiZr2 precipitates,/TiZrBe eutectic structure/rich Al(TiZr)solid solution structure,/TiAl alloy parent material and Al.