Manufacturing Of Zr-based Bulk Amorphous Alloy By Spark Plasma Sintering

Amorphous alloys have attracted great attention due to their excellent high yield strength,high hardness,large elastic limit,high corrosion resistance and superplasticity in the scientific and engineering fields.The limitation of the size of amorphous alloys produced by the conventional rapid solidification method which seriously restricts the practical application of amorphous alloys as structural materials in industrial fields.Compared with the rapid solidification method,the powder metallurgy method can produce a large-sized,complex-shaped,near-net-form bulk amorphous alloy in a wider alloy system and a wider composition range,The preparation of amorphous alloy by discharge plasma sintering technology(SPS)provides a rare opportunity to solve the above problems.Zirconium-based amorphous alloy was used as as the object in this paper to prepare Zr50Ti5Cu27Ni10Al8 amorphous powder by atomization method.The bulk amorphous alloy was prepared by SPS technology.It researched the influence of sintering parameters on the microstructure and properties of the SPS sintering bulk alloys.The amorphous alloy powder was sintered into the bulk alloy by SPS technology.It researched the influence of the sintering temperature,sintering pressure,heating rate and holding time on phase composition,thermodynamic,density,compressive strength properties micro hardness and the microstructure.The results shown that sintering temperature,sintering pressure,holding time and heating rate had a significant effect on the microstructure and mechanical properties of the bulk alloy.The increase of sintering temperature improved significantly the density,compressive strength and vickers hardness of the sintering bulk alloys.But if the sintering temperature was too high,promoting the crystallization and reverse densification of the sintered bulk which can decreased the mechanical properties.The optimum sintering temperature was close to the initial crystallization temperature of 753K.when the density was up to 7.47g/cm3,the compressive strength and vickers hardness reached 1563MPa and 1154HV respectively;As the sintering pressure increases,the bulk alloy underwent different degrees of crystallization,and the precipitated crystal phases were all nanometer-sized.The increase of sintering pressure improved the density,compressive strength and vickers hardness of the sintering bulk alloys.When the sintering pressure increased from 100MPa to 500MPa,the density of the sintering bulk alloys varied from 6.29g/cm3 to 7.47g/cm3,compressive strength increased from 1121MPa to 1563MPa,and the vickers hardness increased from 865Hv to 1154Hv;The increase of holding time promoted the crystallization of amorphous alloy,affecting the density and mechanical properties of the sintering bulk alloys.The result indicated that the sintering bulk alloys showed the excellent mechanical properties,when the holding time was 7min,the density reached 7.51g/cm3,the highest compressive strength 1579MPa and vickers hardness was up to 1181Hv;As the heating rate increased,the degree of crystallization of the sintering bulk alloys gradually decreased and then increased slightly.When the heating rate was 50K/min,the microstructure and mechanical properties of the sintering bulk alloys reached optimum.