Effect of processing parameters on the formation of C-f/LAS composites/Ag-Cu-Ti/TC4 brazed joint

摘要

C-f/LAS composites were successfully jointed to TC4 alloy with Ag-Cu-Ti filler by vacuum brazing. The interfacial microstructure of TC4/C-f/LAS composites joints was characterized by employing scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-diffraction (XRD) and transmission electron microscopy (TEM). The determination of the thin interfacial reaction layer (TiSi2 + TiC layer) was realized by TEM. The effect of holding time on the interfacial microstructure and shear strength were investigated. With the increasing holding time, the thickness of diffusion layer, Ti3Cu4 layer, and TiSi2 + TiC layer increased obviously, on the contrary, that of Ti-Cu intermetallic compound layers decreased gradually. Besides, blocky Ti3Cu4 phase was coarsened when the joint was brazed at 890 degrees C for 20 min, which deteriorated the mechanical properties of the joint dramatically. The interfacial evolution of TC4/C-f/LAS composites joint and the formation of TiSi2, TiC, Ti3Cu4, TiCu and Ti2Cu phases were expounded. The maximum shear strength of 26.4 MPa was obtained when brazed at 890 degrees C for 10 min. (C) 2016 Elsevier Inc. All rights reserved.