摘要
60NiTi(60wt%Ni-40wt%Ti)合金具有高硬度、高弹性模量及优异的耐磨和耐腐蚀性能,在许多领域有潜在的应用价值。本文对激光熔覆方法在316L不锈钢表面制备NiTi涂层的微观组织结构和物相组成进行了分析。结果表明:基材中主要成分Fe和Cr扩散到熔覆涂层中并显著地影响了镍钛涂层的组织结构和性能。熔覆涂层主要组成相为NiTi和Ni_(3)Ti,提高Ni含量可抑制NiTi_(2)析出。第一性原理计算结果显示,Fe和Cr元素易于固溶在B2结构的NiTi相中,并且都倾向于置换晶胞中的Ni原子。Ni_(3)Ti晶胞结构中的Ni和Ti原子各有2个不同的晶位,Fe原子倾向于置换晶胞中Ni-1晶位的Ni原子,而Cr原子倾向于置换晶胞中Ni-2晶位的Ni原子。根据涂层的成分分析结合模拟可知,镍钛合金涂层中NiTi和Ni_(3)Ti相的化学式分别为Ni_(5)Ti_(8)Fe_(2)Cr和Ni_(9)Ti_(4)Fe_(2)Cr。
60 NiTi(60wt%Ni-40wt%Ti)alloy presents higher hardness,high elastic modulus,good abrasion performance and excellent corrosion resistance,making it suitable for various applications in different fields.This paper investigated the microstructure and phase composition of NiTi alloy coating on 316L stainless steel prepared by laser cladding.It shows that the main alloying elements Fe and Cr in the substrate are significantly doped into the cladding coating,which obviously affect the microstructure and properties of Ni-Ti coating.The main phases in the coating are NiTi and Ni_(3)Ti phases.Increase the content of Ni can inhibit the precipitation of NiTi_(2).First-principles calculation based on density functional theory was used to study the phase preference and site preference occupations of the alloying elements Fe and Cr from substrate in NiTi and Ni_(3)Ti phases.The microstructure and phase composition of the coatings were investigated as well.The results show that,NiTi and Ni_(3)Ti are the major phases in the coating.Both Fe and Cr atoms prefer to substitute Ni atom in the NiTi(B2)crystal structure.However,in the Ni_(3)Ti crystal structure,each Ni and Ti atom has two different crystal positions,Fe atom prefers to substitute position Ni-1 and Cr atom prefers to substitute position Ni-2 instead.Combined the experiment and calculation results,the major phases in the coatings after element doping are supposed to be Ni_(5)Ti_(8)Fe_(2)Cr and Ni_(9)Ti_(4)Fe_(2)Cr.
作者
丰玉强
胡正飞
FENG Yuqiang;HU Zhengfei(School of Materials Science and Engineering,Tongji University,Shanghai 201804,China;Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials,Shanghai 201804,China)
出处
《复合材料学报》
EI
CAS
CSCD
北大核心
2024年第2期1030-1037,共8页
Acta Materiae Compositae Sinica
基金
国家自然科学基金(51971163)。
关键词
激光熔覆
镍钛合金
第一性原理
合金元素掺杂
择优占位
表面改性
laser cladding
NiTi alloy
first-principles calculation
alloy doping
site preference
surface modification
