Effects of sinusoidal vibration of casting-roller on interface microstructure of Ti/Al laminated composites by twin-roll casting

Abstract

A new vibration cast-rolling technology of “electromagnetic stirring + dendrite breaking + asynchronous rolling” was proposed with the adoption of sinusoidal vibration of the casting-roller to prepare Ti/Al laminated composites, and the effects of sinusoidal vibration of casting-roller on the interfacial microstructure were investigated in detail. In the interface of traditional cast-rolling materials, the ridge-shaped aluminum materials extend in a straight line or grow transversely into some tiny ridge-shaped branches which look like a quasi-cleavage fracture. With the enhancement of the casting-roller vibration, a large area of hilly aluminum materials in the interface is bonded or present equiaxed dimples gathering to form honeycomb network morphology, which presents ductile fracture characteristics. The vein patterns and morphology differentiation in the interface show that the density and uniformity of composite intensity distribution can be enhanced by increasing the vibration frequency, but the level of enhancement is not that much obvious. The hilly morphology and equiaxed dimples in the interface show that the unit composite strength can be enhanced by increasing the vibration amplitude, while the density of strength distribution is sparse. Under the combined effect of “amplitude + frequency,” the toughness and composite quality of the interface are enhanced by the uniform superposition of the discrete strengths. The area ratio of aluminum bonded to titanium side interface (81%) is 3 times higher than that of traditional cast-rolling material (22%) on the condition of ductile fracture of cast-rolling material with strong vibration (amplitude 0.87 mm, vibration frequency 25 Hz) of casting-roller, and the bonding strength (27.0 N/mm) is twice as high as that of traditional cast-rolling materials (14.9 N/mm), which indicates that the ductile connection between the interface layers can be greatly enhanced by vibration roll-casting.