Effects Of Micro Tion Microstructure And Properties Of Zr-based Amorphous Alloy

Amorphous alloys have excellent physical and chemical properties due to the unique atomic structure,and have broad application prospects in the fields of electronic,mechanical,chemical engineering,national defense and so on.Up to now,the fabrication of bulk amorphous alloy with low-cost is still a challenging problem,which limits its application.In this paper,Zr_55-xAl₁₀Ni₅Cu₃₀Ti_x?x=0,1,3 and 5?amorphous alloys were prepared by the industrial raw materials and copper mold casting method and continuous-casting method.The variations of the micro-structure and properties of Zr-based amorphous alloys at different process conditions were studied,which could have certain reference value for the low-cost preparation of bulk amorphous alloy.First of all,Zr₅₅Al₁₀Ni₅Cu₃₀ amorphous alloy was prepared by copper mold casting method.The effects of pouring temperature and sample size on glass forming ability and mechanical properties of glass were studied.The results showed that the pouring temperature had an important influence on the mechanical and properties of the amorphous alloys.Optimizing the pouring temperature decreased the nucleation of the alloy liquid during cooling and solidification process,and obtained the amorphous alloys with decent morphology.When the pouring temperature is in the range of 900°C¹000°C,the glass forming ability of the amorphous alloys is enhanced with the increase of the molten temperature in the copper mold casting method.As the pouring temperature is higher than1000°C,the actual cooling rate of the alloy decreased with the increase of the molten temperature,and the amorphous phase was weakened.Moreover,the amorphous components in the alloy improved the mechanical properties of the alloy.Higher amorphous component in the alloy leads to greater hardness of the alloy.With the increase of the alloy size,the cooling rate of the alloy was reduced,resulting in the increase of crystallization for the sample decreased greatly the forming ability of amorphous alloy.In the preparation process of Zr₅₅Al₁₀Ni₅Cu₃₀ amorphous alloy by the horizontal continuous casting method,the design scheme of casting mould was based on the shrinkage characteristics of Zr-based amorphous alloy.The suitable parameters included mould temperature,solid-liquid interface position,traction speed and cooling distance,and they were selected according to the thermal conductivity of copper rod and the properties of alloy melt.The specific values were described as follow:the mold structure with a type of straight barrel,the mould temperature of 900°C¹000°C,the solid-liquid interface position of 5 mm²0 mm,the traction speed of 1 mm/s⁹ mm/s,the cooling distance of 20mm⁶0 mm,and the cooling dose of 3 L/min.After a detail research for the two important process parameters of mould temperature and traction speed,it was found that the mould temperature could significantly control the initial temperature of the melt.When the mould temperature was in the range of 900°C¹000°C,the temperature gradient increased with the mould temperature,which favored the forming ability of amorphous alloy,to prepare the alloy with good structure and high performance.However,if the cooling rate was not high enough,it was difficult to prepare the casting sample and the amorphous structure would not be formed during the solidification.If the mould temperature was under 900°C,the melt temperature was not high enough to make the alloy solidified easily at a suitable time,and the temperature gradient is not enough to form an amorphous structure,resulting in the casting became difficult.The traction speed controlled the cooling rate of the melt.The cooling rate determined the temperature gradient in the inside and outside of the mold.When the traction speed was in the range of 1 mm/s⁹ mm/s,the cooling rate increased with the traction speed,and the more amorphous structure could be found in the casting,which could increase the hardness of the alloy.However,the over-quick traction speed would cause the prepared alloy with high brittleness and decreased toughness.Zr_55-xAl₁₀Ni₅Cu₃₀Ti_x?x=0,1,3 and 5?amorphous alloys were prepared by the copper mold casting method.The effects of addition of Ti on the glass forming ability,thermal stability and mechanical properties of Zr-based amorphous alloys were investigated.It was found that the addition of Ti increased the glass forming ability of Zr-based amorphous alloy.However,the stability of amorphous state did not increase correspondingly with the increase of Ti content.The appropriate content of Ti improved significantly the mechanical properties of the alloy.Amorphous composite material of Zr₅₄Al₁₀Ni₅Cu₃₀Ti had excellent mechanical properties,including the fracture strength of 1639.28 MPa and the plastic strain of 2.1%.Interestingly,a large area with fine and deep vein pattern was distributed in the smooth region of fracture surface.