热处理工艺和W丝特性对W丝增强锆基非晶复合材料残余应力的影响

Effects of Heat Treatment Processes and W Wire Properties on Residual Stress in W Wire Reinforced Zr-Based Metallic Glass Composites

为了调控W丝增强锆基非晶复合材料在制备过程中产生的残余应力,采用中子衍射技术对不同热处理条件后的W丝增强的非晶复合材料进行应力分布状态的测量。实验结果表明,W丝轴向方向具有强烈的<110>织构和较低的精修残差值(R_(wp)),证实了精修数据的准确性。首先,在200℃下回火处理30 min可以有效降低非晶复合材料内部的残余应力;但当回火时间增加到60 min时,其应力会再次增大。通过对W丝进行烧氢处理,发现非晶复合材料内部的残余应力可以有效地降低。另外,非晶复合材料内部的残余应力对W丝直径变化并不敏感。

Bulk metallic glasses(BMGs)are exhibit a unique atomic structure and have a longrange disorder but short-to-medium-range order,contrasting sharply with the periodic arrangements found in crystalline materials.This distinct arrangement grants BMGs exceptional properties such as high strength,significant elastic limits,and high resistance to corrosion and wear.However,BMGs are brittle owing to localized shear band propagation during deformation under load,particularly at temperatures below their glass transition temperature.This brittleness restricts their practical applications,prompting researchers to explore methods to enhance their ductility.One prominent approach involves the development of bulk metallic glass composites(BMGCs)via incorporating a secondary phase that effectively mitigates the single shear band instability and promotes multiple shear bands to partake in plastic deformation,significantly enhancing the room-temperature ductility.BMGCs reinforced with W wire are noteworthy owing to the high density and strength of W,making these materials highly applicable in the defense sector.By embedding W wires homogeneously into a BMG matrix such as Vitreloy 1(Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10.0)Be_(22.5),atomic fraction,%),the resulting composite has high compressive strength and ductility.Despite these benefits,the production of W wire-reinforced BMGCs inevitably introduces thermal residual stresses owing to the differences in the coefficients of thermal expansion of the composite components.These stresses can significantly affect the mechanical properties of the BMGCs.Advanced nondestructive techniques such as neutron diffraction have become indispensable tools for evaluating the internal stress distribution within such materials.Neutron diffraction enables the measurement of stresses deep within the materials,providing a comprehensive view of the entire sample volume,which is crucial for optimizing the manufacturing processes and enhancing the performance of the BMGCs.This work aims to comprehensively investigate the effects of various processing parameters,such as the diameter of the W wires and temperature,on the residual stresses within W wire-reinforced BMGCs.By using neutron diffraction to analyze the effects of annealing treatment of W wires in hydrogen,heat treatment duration of BMGCs,and W wire diameter on residual stresses,this work aims to finely tune the internal stresses during the manufacturing process,thereby laying a foundation for optimizing and improving the material properties of W wire-reinforced BMGCs.The results reveal a strong<110>texture along the axial direction of the W wire and a low refined residual value(R_(wp)),confirming the accuracy of the refined data.The tempering process demonstrates a complex influence on the control of residual stresses within W wire-reinforced BMGCs.Measurements and analyses of residual stresses after different tempering treatments reveal that a 30 min temper at 200oC effectively reduces residual stresses.However,extending the tempering duration to 60 min leads to the reaccumulation of stresses owing to complex reactions within the BMGCs.In addition,a comparative analysis of W wire-reinforced BMGCs annealed in the present and absence of hydrogen indicates that the former significantly improves the surface quality of W wires,thereby reducing the residual stresses in the BMGCs.After annealing in hydrogen,the diameter of W wires increases from 0.2 mm to 0.3 mm,which has little effect on the overall stress distribution.