摘要
目的研究Cr元素含量对TC21钛合金表面激光熔覆Ni-Al涂层组织与性能的影响,改善其表面性能。方法利用激光熔覆技术在TC21钛合金表面制备不同Cr含量的Ni-Al涂层,采用带有能谱仪(EDS)的扫描电子显微镜(SEM)、X射线衍射仪(XRD)对熔覆层的显微组织、物相组成进行分析,采用显微硬度计和材料表面性能综合测试仪测试熔覆层的硬度分布和耐磨性能。结果熔覆层表面质量良好,未添加Cr元素时,熔覆层主要由Ni(Al,Ti)、Ni2AlTi、TiNi等物相组成;添加Cr元素后,熔覆层中有α-Cr沉淀相析出,并且随着Cr元素含量的逐渐提高,TiNi、Ni2AlTi、α-Cr等物相的相对含量逐渐增加。熔覆层主要由Ni(Al,Ti)枝晶组织与其周围呈网状分布的TiNi、Ni2AlTi、α-Cr晶间组织构成。熔覆层的显微硬度均提高到基体的2倍左右,Cr元素对提高Ni-Al涂层显微硬度的影响不大,但能使其显微硬度波动减小,趋于平稳,熔覆层的韧性随着Cr元素含量的增加而不断提高。当Cr元素添加量为20%(原子数分数)时,耐磨性最好,约为基体的2.948倍。结论Cr元素的添加,有利于熔覆层中α-Cr相的析出和TiNi/Ni2AlTi共晶组织的生成,能有效降低熔覆层的室温脆性,提高塑韧性及耐磨性能。
The work aims to study the effects of chromium(Cr)element content on the microstructures and properties of laser cladding Ni-Al coating on TC21 titanium alloy to improve the surface properties.The Ni-Al coatings with different Cr contents were prepared on the surface of TC21 by laser cladding.The microstructures and phases of cladding layer were analyzed with scanning electron microscopy(SEM),energy dispersive spectrometry(EDS)and X-ray diffractometry(XRD).The microhardness distribution and wear resistance were tested with microhardness tester and multifunctional material surface performance tester,respectively.The results showed that the surface quality of cladding layer was good.The main phases of the cladding layer were Ni(Al,Ti),Ni2AlTi and TiNi when there was no Cr element.However,α-Cr precipitation phase appeared after the Cr element was added into the cladding layer,and the relative content of TiNi,Ni2AlTi,α-Cr increased gradually with the increase of Cr content.The microstructure of cladding layer was mainly composed of Ni(Al,Ti)dendritic structure and its surrounding reticular intergranular structure of TiNi,Ni2AlTi andα-Cr.The microhardness of the cladding layers increased to about 2 times of the substrate.Although the Cr content had little effect on improving the microhardness of the Ni-Al coating,it was able to reduce the microhardness fluctuation of the cladding layer to stable.The toughness of the cladding layer was improved with the increase of Cr content.When 20%atomic percentage of Cr was added into the cladding layer,the wear resistance was the best,about 2.948 times than that of the substrate.It reveals that Cr element contributes to the precipitation ofα-Cr phase and the generation of TiNi/Ni2AlTi eutectic structure.It effectively reduces the room temperature brittleness,and improves the toughness and wear resistance of the cladding layer.
作者
张显
胡记
隋欣梦
马欣然
张维平
ZHANG Xian;HU Ji;SUI Xin-meng;MA Xin-ran;ZHANG Wei-ping(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2020年第1期311-317,共7页
Surface Technology
