Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption...Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption and competitive behavior of complex environmental molecules.This study investigated the adsorption and dissociation behavior of a series of gas-phase molecules(O_(2),H_(2)O,SO_(3),S_(2),H_(2)S,Cl_(2)and HCl)on the NiAl(110)surface using first-principles calculations.The findings reveal a mechanism of competitive adsorption and dissociation,with two distinct adsorption dissociation behaviors observed upon the introduction of Pt or Hf elements.Pt-doping inhibits the surface adsorption behavior of self-catalytic molecules,while Hf significantly enhances the adsorption and dissociation of oxygen-carrying molecules.By preparing three types of NiAl-phase coatings(β-NiAl,(Ni,Pt)Al,and Hf-(Ni,Pt)Al)and conducting corrosion tests in the presence of NaCl or Na_(2)SO_(4),it is determined that the excellent corrosion resistance of Hf-(Ni,Pt)Al can be attributed to the combined effects of Pt in delaying corrosion reactions and Hf in promoting the formation of a protective oxide scale.A comprehensive analysis,combining first-principles calculations and experimental observations,was conducted to elucidate the corrosion mechanisms of three coatings in different corrosion mediums.展开更多
目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米N...目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米NiAl粉体,采用真空热压烧结炉将NiAl粉体与Fe粉混合烧结,得到块体试样。采用扫描电镜(Scanning electron microscopy,SEM)进行微观组织观察,采用能谱仪(Energy dispersive spectroscopy,EDS)、X射线衍射仪(X-ray diffraction,XRD)以及透射电子显微镜(Transmission electron microscopy,TEM)进行物相分析,并测试不同NiAl含量的铁基合金的硬度、密度、室温压缩性能以及600℃的抗氧化性能。结果合金的硬度、抗压强度随NiAl含量先增后降。当NiAl的质量分数为50%时,合金硬度为35.2HRC,抗压强度为2530MPa,密度为6.68g/cm^3,较未添加NiAl时,合金的抗压强度提升了239.6%,密度降低了14.5%。θ=600℃、t=1200min时,其表面氧化增重较纯铁降低了37.9%,此时NiAl相的尺寸约为100~200nm,组织最为均匀,致密度较高。结论纳米NiAl相在降低铁基合金密度的同时,能有效提升其力学性能与抗氧化性能,但由于B2结构的纳米NiAl相为一种硬脆相,当其含量过高时,会极大程度地降低合金的力学性能。展开更多
基金the sponsorship by the National Natural Science Foundation of China(Nos.51671202 and 52301116)the Fundamental Science Center for Aviation and Gas Turbine Engines(No.P2021-A-IV-002-001)+1 种基金supported by the National Science and Technology Major Project(No.J2019-IV-0006-0074)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2).
文摘Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption and competitive behavior of complex environmental molecules.This study investigated the adsorption and dissociation behavior of a series of gas-phase molecules(O_(2),H_(2)O,SO_(3),S_(2),H_(2)S,Cl_(2)and HCl)on the NiAl(110)surface using first-principles calculations.The findings reveal a mechanism of competitive adsorption and dissociation,with two distinct adsorption dissociation behaviors observed upon the introduction of Pt or Hf elements.Pt-doping inhibits the surface adsorption behavior of self-catalytic molecules,while Hf significantly enhances the adsorption and dissociation of oxygen-carrying molecules.By preparing three types of NiAl-phase coatings(β-NiAl,(Ni,Pt)Al,and Hf-(Ni,Pt)Al)and conducting corrosion tests in the presence of NaCl or Na_(2)SO_(4),it is determined that the excellent corrosion resistance of Hf-(Ni,Pt)Al can be attributed to the combined effects of Pt in delaying corrosion reactions and Hf in promoting the formation of a protective oxide scale.A comprehensive analysis,combining first-principles calculations and experimental observations,was conducted to elucidate the corrosion mechanisms of three coatings in different corrosion mediums.
文摘目的通过机械合金化与热压烧结相结合的方法制备含有B2结构纳米NiAl相的铁基合金,研究不同含量(质量分数为30%、40%、50%、60%)的纳米NiAl相,对合金显微组织及力学性能的影响。方法以Ni粉和Al粉为原材料,通过高能球磨法制备B2结构纳米NiAl粉体,采用真空热压烧结炉将NiAl粉体与Fe粉混合烧结,得到块体试样。采用扫描电镜(Scanning electron microscopy,SEM)进行微观组织观察,采用能谱仪(Energy dispersive spectroscopy,EDS)、X射线衍射仪(X-ray diffraction,XRD)以及透射电子显微镜(Transmission electron microscopy,TEM)进行物相分析,并测试不同NiAl含量的铁基合金的硬度、密度、室温压缩性能以及600℃的抗氧化性能。结果合金的硬度、抗压强度随NiAl含量先增后降。当NiAl的质量分数为50%时,合金硬度为35.2HRC,抗压强度为2530MPa,密度为6.68g/cm^3,较未添加NiAl时,合金的抗压强度提升了239.6%,密度降低了14.5%。θ=600℃、t=1200min时,其表面氧化增重较纯铁降低了37.9%,此时NiAl相的尺寸约为100~200nm,组织最为均匀,致密度较高。结论纳米NiAl相在降低铁基合金密度的同时,能有效提升其力学性能与抗氧化性能,但由于B2结构的纳米NiAl相为一种硬脆相,当其含量过高时,会极大程度地降低合金的力学性能。
基金Supported by the National Natural Science Foundation of China(10972190)Scientific and Technological Project of Hunan Science and Technology Commission(2010FJ3132)
