摘要
在预热400℃的锻态TA15合金基材上,应用激光沉积制造技术制备了具有3层梯度层的TA15/GH4169梯度结构,研究了GH4169含量对各梯度层组织与性能的影响。利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线能量色散谱仪(EDS)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机对沉积样件进行了显微组织观察、元素分布检测、物相检测、显微硬度与室温耐磨性能分析。研究表明,所制备的沉积试样无宏观裂纹缺陷且组织致密。沉积态TA15侧组织为贯穿多个沉积层的β柱状晶组织,晶内为典型的网篮组织,GH4169侧为沿沉积方向生长的柱状晶组织,枝晶间析出不规则的Laves相,过渡区内形成了两相固溶体和脆性金属间化合物(Ti_(2)Ni,TiNi_(3))。各梯度层随GH4169含量的增加,显微硬度和耐磨性能均不断提高,25%TA15性能最好,其硬度和摩擦系数分别为HV_(0.2)537和0.33,较100%TA15梯度层硬度值提高了97%,摩擦系数降低了72%。本研究将为最终成形TA15/GH4169梯度复合结构提供参考依据。
In the field of aerospace,most of the hot-end parts in engines do not work at constant temperature,and the performance requirements of different positions in the same part are also different.Therefore,if the titanium alloy/superalloy gradient structure can be applied to the engine matrix in practice,the engine weight can be significantly reduced while the thrust is ensured during flight,thereby the flight efficiency of the aircraft could be improved effectively.So,the titanium alloy/superalloy gradient structure is of great potential significance in actual application.Laser deposition manufacturing technology has technical advantages in the preparing of gradient composite structure.The difference of thermal-physical parameters of titanium alloy and superalloy produces severe residual thermal stress during the laser deposition manufacturing process,which leads to the bad forming quality of the transition interface of titanium alloy/superalloy gradient composite structure,and substrate preheating can solve this problem effectively.TA15/GH4169 gradient composite structure with three gradient layers was fabricated by laser deposition manufacturing technology on forged TA15 alloy substrate preheated at 400 ℃ by constant-temperature heating platform.OLYMPUS optical microscope(OM),JSM-6700 scanning electron microscope(SEM)and X-ray diffractometer(XRD)were used to observe the microstructure and phase change of each gradient layer,and the EDS module on the scanning electron microscope was used for surface scanning of element distribution in designated area.The HVS-1000 A microhardness tester and the HT-1000 ball-disk friction and wear tester were used to measure the microhardness and abrasion properties of different positions of the gradient structure along the gradient direction.The effect of GH4169 content on the microstructure and properties of TA15/GH4169 gradient layer was investigated.The results showed that the TA15/GH4169 gradient structure with three gradient layers was successfully fabricated and the deposited samples were fully dense and defect-free.The main elements Ti,Ni,Cr and Fe in TA15 and GH4169 alloys were distributed reasonably along the gradient direction without element mutation,and the gradient transition zone greatly alleviated the difference in composition between the two materials.The macrostructure of as-deposited TA15 side was composed of columnar crystals passing through multiple sedimentary layers,the microstructure was typical basket structure,and in the grains appeared primarily α phase and lamellar phase.Some α phases were obviously coarsened and the length-width ratio was about 6.While the GH4169 side structure presented columnar dendrites growing epitaxially through the deposition layers,with strong orientation,the growing direction tended to be parallel to the laser deposition direction,and irregular Laves phases were precipitated between dendrites.With the increasing of GH4169 content in the gradient transition zone,the phase composition was α→ α+Ti_(2)Ni → Ti_(2)Ni+TiNi_(3)→ Ti_(2)Ni+TiNi_(3)+γ→γ.The 75%TA15 gradient layer was mainly composed of Ti_(2)Ni(the strengthening phase distributed on Ti based solid solution),the microstructure of 50% TA15 gradient layer was mainly composed of Ti_(2)Ni and TiNi_(3),and the microstructure of 25%TA15 layer was composed of a large number of TiNi_(3) distributed in Ni matrix.The microhardness of each gradient layer increased obviously with the increasing of GH4169 content,and the hardness of 25%TA15 layer reached the maximum value of HV_(0.2)537,increasing by 97% compared with that of 100%TA15 gradient layer.The wear scar width and the wear weight loss decreased with the increasing of GH4169 content in each gradient layer.The friction coefficient of 25%TA15 layer decreased to the lowest value of 0.33,which was 72% lower than that of TA15 layer.The substrate preheating effectively alleviated the stress between the different materials of titanium alloy and superalloy during the laser deposition process,reduced the temperature gradient between the cladding material and the base material,and made the temperature field of the forming process more uniform and stable.The TA15/GH4169 gradient structure of good quality was achieved by designing three gradient layers with different proportions.The comprehensive performance of 25%TA15 layer was the best.Because more strengthening phases with high hardness and face-centered cubic crystal structure were precipitated in 25%TA15 layer compared with that of 100%GH4169 layer.This study would provide basic data for the final formation of TA15/GH4169 gradient composite structure.
作者
何波
王晨
孙长青
杨光
王向明
苏亚东
He Bo;Wang Chen;Sun Changqing;Yang Guang;Wang Xiangming;Su Yadong(School of Mechatronics Engineering,Shenyang Aerospace University,Shenyang 110136,China;Mechanical College,Shenyang Institute of Engineering,Shenyang 110136,China;AVIC Shenyang Aircraft Design&Research Institute,Shenyang 110035,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第1期19-26,共8页
Chinese Journal of Rare Metals
基金
国家重点研发计划项目(2016YFB1100504,2017YFB1104002)
国防科技创新特区项目(18-H863-31-ZD-003-001-01)
辽宁省教育厅科学研究项目(L201738和LQN201722)资助。
