激光重熔对Ti基非晶合金微观结构及性能的影响  

Effect of Laser Remelting on Microstructure and Properties of Ti⁃Based Amorphous Alloys

作　　者：张浩杰 陈志刚 冯伟 侯纪新 于云鹤 朱朝晖 谭洪 夏志新 Zhang Haojie;Chen Zhigang;Feng Wei;Hou Jixin;Yu Yunhe;Zhu Chaohui;Tan Hong;Xia Zhixin(School of Iron and Steel,Soochow University,Suzhou 215021,Jiangsu,China)

机构地区：[1]苏州大学沙钢钢铁学院,江苏苏州215021

出　　处：《中国激光》2024年第24期34-46,共13页Chinese Journal of Lasers

基　　金：国家重点研发计划“增材制造与激光制造”重点专项(2023YFB4603400);国家自然科学基金企业创新发展联合重点支持项目(U23B2073);国家自然科学基金叶企孙基金重点支持项目(U2341254)。

摘　　要：探讨了激光重熔处理对Ti基非晶合金微观组织结构及力学性能的影响。通过分析温度场和不同深度位置的热历史,发现熔池不同深度处的冷却速度均超过Ti基非晶合金的临界冷却速度,导致熔池在冷却凝固后形成非晶态结构。随着熔池深度的增加,熔体的冷却速度逐渐降低,非晶结构中的自由体积含量也随之减少。这种自由体积含量呈梯度的减小减少了剪切带的扩展,使得硬度随着熔池深度的增加而逐渐提高。在热影响区,由于熔池的热影响,晶相析出形成非晶复合结构。然而,不同深度处的热影响区受到激光重熔高温驻留时间和冷却速度的差异影响,晶相的尺寸和密度随着深度的增加而呈梯度变化。晶相的存在阻碍了剪切带的扩展,因此热影响区的硬度显著高于熔池和基板的非晶区。经过激光重熔处理后,Ti基非晶合金形成了含有熔池非晶结构、热影响非晶复合结构和基板非晶结构的梯度异质结构,这种结构的变化导致了硬度的相应变化。不同的激光工艺会导致样品的梯度异质结构发生变化,而合理的异质梯度结构能够阻碍单一剪切带的扩展,从而提高Ti基非晶合金的塑性变形能力。Objective Ti-based amorphous alloys have received significant attention owing to their low density,high specific strength,superior corrosion resistance,and relatively low fabrication cost,which render them promising for widespread application in fields such as national defense,aerospace,sports,and medicine.However,they present some mechanical performance issues such as low plasticity.Studies have shown that introducing heterogeneous structures into metallic materials can improve their mechanical properties.Performing laser remelting on Ti-based amorphous alloys can create gradient heterogeneous structures in their depth direction,thus improving their mechanical performance.Currently,studies regarding the introduction of heterogeneous structures into amorphous alloys via laser remelting are limited.In this study,by performing microscopic analyses and numerical simulations of temperature fields,we investigate the microstructure evolution of laser-re-melted Ti-based amorphous alloys and its effect on their mechanical properties.The aim of this study is to provide experimental and theoretical support for understanding the mechanism of laser-induced heterogeneous structures and its effect on the properties of amorphous alloys.Methods We prepare Ti-based amorphous alloys via vacuum suction casting,followed by laser remelting.First,the microstructure of the laser-re-melted Ti-based amorphous alloys is analyzed using micro-area X-ray diffraction(XRD)and scanning electron microscope(SEM).Subsequently,a numerical simulation of the temperature field during laser remelting is conducted to analyze the thermal histories of different regions after laser remelting.Microstructure analyses and temperature-field simulations are performed to elucidate the effect of laser remelting on the structure of Ti-based amorphous alloys.Subsequently,hardness testing is performed along the depth direction after laser remelting to examine the trend of mechanical-property changes induced by the heterogeneous structure.Finally,various processes ar

关 键 词：激光重熔 Ti基非晶合金 异质结构 显微硬度 

分 类 号：O436[机械工程—光学工程]