Preparation And Mechanical Properties Of Zr-based BMG/Cu Composites

Bulk metallic glass （BMGs） have many advantages over crytalline alloys since theyhave ultra high strength, large elastic deformatiom limit, superior corrosion and wearresistance. At room temperature, the deformation of the amorphous alloy isconcentrated in one or several shear zone leading to the poor plasticity in this case.Thereby, it limits the applications of amorphous alloy as the structural material. As aresult, to improve the plasticity of the amorphous alloy at room temperature, theeffective method is to limit the localization and extension of the shear deformation ofamorphous alloys and increase the number of moving shear zone. If the layeredcomposite material consisting of the the plastic phase and amorphous alloy is made bythe hot-pressing method, it is expected to raise the plasticity of amorphous alloy theroom temperature. In this paper, we prepared the Zr₆₀Cu₂₅Al₁₀Fe₅amorphous alloy andstudied the the deformation behaviors in the supercooled liquid region firstly. Then, itwas to explore the connection technology between bulk amorphous and pure coppe.According to this, the layered composite material including Zr-based BMG/Cu wasmade and it studied the influence of temperature and holding time on themicro-structure and mechanical properties of the prepared composite materials. Themain research results are as follows:（1） The deformatiom behavior in supercooled liquid region of the Zr-basedamorphous were studied. The platy Zr₆₀Cu₂₅Al₁₀Fe₅amorphous alloy prepared bysuction casting of copper. Via the characterization of DSC, we know that the glasstransition temperature （Tg） and the crystallization temperature （T_x） were648K and750K respectively, and the width of the supercooled liquid region （ΔT=T_x-T_g） was102K. The deformation model of amorphous in the supercooled liquid region wasdepended on the temperature and the strain rate；（2） The diffusion bonding between amorphous alloy and copper were studied. Bythe connection the Zr-based BMG and Cu under the condition that the temperature wasbetween400℃-440℃with different soaking time, the load was150MPa, the resultindicate that the temperature and the soaking time are important factor to the quality ofthe connection interface. Under the condition that the holding time was90min，the load was150MPa and the temperature range was with in420℃, the diffusion effect ofCu/Zr60achieved a total metallurgical combination; The diffusion capacity of Cu atomin the amorphous was lower than in the spread of the spread of he crystal alloy; Throughthe theoretical analysis, the diffusion bonding time between Zr-based amorphous andcopper was longer than Zr-based amorphous under the temperature of420℃；（3） The amorphous/Cu laminated composite were prepared under differentconditions by hot pressing. Zr-based BMG/Cu composite material was successfulprepared when the condition was at the temperature of420℃and440℃, a load of150MPa, the loading rate of2×10^-3s^-1and heat preservation time of90min. The interfacebonding shear strength of the composites were63MPa and90MPa respectively. At thetemperature of420℃, the amorphous layer of the laminar composite had no obviouscrystallization and it kept the amorphous structure. However, when the temperature was440℃, the crystallization had been taken palce in the amorphous layer partly and it wasmainly due to the production of Zr₂Cu crystallization phase. At room temperature, thecompression strength of the laminar composite which was hot-pressed in420℃was850Mpa and it also showed a certain plasticity; while the laminar composite made in440℃indicated no plasticity. The strength of the above laminar composite met the ruleof mixture in the strength of laminar composite. The reason that the laminar compositehot-pressed in420℃performanced plasticity at room temperature was that the Cu layerhas a negative influnce on the formation and propagation of the shear zone and crack inthe amorphous layer.