Availability of in-situ reinforced active-transient liquid phase bond with good wettability for 70 vol.% SiCp/A356 composite using Al-Mg-Ga-Ti interlayer

Abstract

For transient liquid phase bonding of as-cast 70 vol. % SiCp/A356 composite, Al-24Mg-16Ga-1Ti (wt.%) active braze was designed by adding Ti as melting point increaser (MPI) for Al into Al-Mg-Ga active alloy near eutectic composition to produce in-situ reinforcement by precipitating a fine and dispersive Ti-containing intermetallic compound as reinforcement within the solid-solution bond seam after isothermal solidification. Bonding was performed at three temperature levels of quasi-melting (450 o C), just fully melting (500 o C), and over melting (550 o C) for the braze under 0.5 ~ 1.75 MPa in argon. The braze was able to produce fine (less than 1 μm) and dispersive Ti-containing precipitated phase (Al-2Mg-1Ga-0.5Ti, at.%) as in-situ reinforcement only at 500 o C under medium pressure (1~1.5 MPa), increasing bond seam microhardness by 30 Hv over the matrix. The braze robustly showed good wettability for each temperature due to the matrix dissolution and detectable amorphous reaction products containing Mg and Ga on SiC surface. Higher temperature caused coarsening of needle-like Si-containing Al-Si-Ti precipitated phase while higher pressure produced blocky Al3Ti with a shell of Mg and Ga. Sound joint produced at 500 o C under 1.5 MPa with 118.6 MPa shear strength (98.8% parent composite) fractured completely within the composite.

Interfacial Behavior and Shear Strength of Al-25Si-4Cu-1Mg Joints by Transient Liquid Phase Bonding with Cu as Interlayer

“…The transient liquid phase (TLP) brazing method has been successfully used for joining Albased composite materials [16,17], and its application on Al-Si alloys was also investigated. Wang et al [18][19][20][21] completed the joining of Al-Si alloy by transient liquid phase brazing under ultrasonic induction with Zn-based solder and Sn-51In solder. Xu [22] et al successfully completed the welding between 6061 aluminum alloy and Al-27Si alloy with transient liquid phase brazing.…”

Joining of Hypereutectic Al-50Si Alloys Using Lead-Free Brazing Filler Glass in Air

“…As the chemical properties of silicon carbide particles are quite different with the base aluminum alloy, the joining of SiC p /Al MMCs has been a difficult point. Joining methods for SiC p /Al MMCs include flux-free diffusion joining [ 4 ], transient liquid phase bonding (TLP) [ 9 ], vacuum brazing [ 10 ], ultrasonic brazing [ 11 ], friction stir welding [ 3 ], mechanical vibration agitation brazing [ 12 , 13 ] and semi-solid welding [ 14 , 15 ], etc. Among the above-mentioned joining methods, brazing has good joining effect and economic efficiency.…”