Joints of continuous carbon fiber reinforced lithium aluminosilicate glass ceramics matrix composites to Ti60 alloy brazed using Ti-Zr-Ni-Cu active alloy

Continuous carbon fiber reinforced lithium aluminosilicate glass ceramics matrix composites(C_f/LAS composites) are joined to Ti60 alloy vacuum brazed using Ti-Zr-Ni-Cu brazing alloy. The effects of the brazing temperature on the interfacial microstructure and mechanical properties of brazed joints are investigated in details. The interfacial microstructure varies apparently with an increase of the brazing temperature. The thicknesses of the banded Ti solid solution(Ti(s, s)) and the reactive layer between Cf/LAS composites and the interlayer grow gradually. The mechanical properties of brazed joints increase firstly and then decrease with an increasing temperature. In addition, a joint that is brazed at 980 °C for 10 min shows the highest shear strength of$38.13 MPa. At the same time, the fracture paths of brazed joints also change as the temperature increases. When the brazing temperature is 950 °C, the fracture position is in the TiC + ZrC +Ti_2O + ZrSi_2+ Ti_5Si_3 layer on the composite side. When the brazing temperature is 980 °C, the fracture position is on the side of the braze seam(Ti, Zr)2(Ni, Cu), Ti_2O + ZrSi_2+ Ti_5Si_3 layer,and carbon fiber in the composite material. When the brazing temperature is 990 °C, the fracture position is in the Ti_2O + ZrSi_2+ Ti_5Si_3 layer on the composite side and the carbon fiber in the composite material.

Fabrication of Si_(3)N_(4)/Cu direct-bonded heterogeneous interface assisted by laser irradiation

Joining of ceramic and metal is a key component in microelectronic device manufacturing,in which the integrity of bonded interface is critical in the performance and stability of the devices.Current methods with a problem of thick transition layer at the interface impeded heat flow,which degraded device service life seriously.Herein,we propose a laser-assisted bonding approach to join ceramic to metal directly without any intermediate material.By focusing the laser on the surface of β-Si_(3)N_(4) ceramic,the Si microcrystalline layer with stacked α-Si_(3)N_(4) nanocrystals was prepared first.The face-centered cubic(fcc)Si and hexagonal close-packed(hcp)β-Si_(3)N_(4) substrate take the coherent orientation relations of[001]_(fcc)║[0001]_(hcp) and(220)_(fcc)║(10■0)_(hcp).Then,the defect-free Si_(3)N_(4)/Cu bonded interface obtained by the reaction of the formed Si and Cu at elevated temperature in the 805-900℃range for 30 min demonstrated a strong and stable joining of ceramic to metal.The introduction of the laser provides a novel approach to join ceramics to metals,and the ceramic/metal component is expected to be a new configuration for package substrate in high-power device applications.

Wetting behavior of AgCu-4.5Ti filler reinforced by carbon nanotubes on C/C composite

The effect of Carbon Nanotubes(CNTs)content on the wettability of AgCu-4.5Ti+x CNTs(wt%)composite filler alloys on C/C composite was investigated.The results show that the added CNTs reacted with element Ti in the filler and produced the dispersed fine in situ synthesized TiC particles,which increased the consumption of element Ti and provided the nucleus for the growth of Ti-Cu compounds simultaneously.The above effects of introducing CNTs,inhibited the formation of Ti-Cu compounds,also changed the distribution of compounds,which dramatically influenced the interfacial microstructure and characteristics of wetting behavior.The increase of CNTs content refined and dispersed coarse Ti-Cu compounds,decreased the initial spreading temperature,and improved the wettability,but high content of CNTs(more than 0.3 wt%)decreased the wettability of the filler alloy.The wetting interfacial microstructure of corresponding composite filler alloys were analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-ray Spectrometer(EDS)and Transmission Electron Microscope(TEM),which consisted of TiC,TiCu,TiCu;and TiCu;compound.The typical wetting behavior of AgCu-4.5Ti+0.3wt%CNTs composite filler on C/C composite was divided into four stages.The effect mechanism of CNTs content on the wetting behavior was proposed.