铁素体/马氏体(ferrite/martensite,F/M)耐热钢中铌、钛等强碳化物形成元素容易在钢液凝固过程形成粗大的液析第二相,影响钢的蠕变和疲劳性能。调控液析第二相的成分和尺寸对提高钢的力学性能具有重要意义。电渣重熔和稀土改性都是调控...铁素体/马氏体(ferrite/martensite,F/M)耐热钢中铌、钛等强碳化物形成元素容易在钢液凝固过程形成粗大的液析第二相,影响钢的蠕变和疲劳性能。调控液析第二相的成分和尺寸对提高钢的力学性能具有重要意义。电渣重熔和稀土改性都是调控钢中第二相的常用方法,两者共同作用对F/M耐热钢中液析第二相的影响缺乏相关研究。本研究旨在探究含铈的10Cr1Si F/M钢电渣重熔后第二相的析出特征。采用扫描电子显微镜(scanning electron microscope,SEM)和ASPEX自动扫描电镜等方法,对含铈的10Cr1Si钢电渣锭中的液相第二相进行统计分析。结果表明,电渣锭顶部、底部、中心、边缘不同位置中主要存在3类液相第二相,即黑色球状稀土氧化物CeAlO_(3)、多边形状氮化物TiN和针状、条状的碳化物NbC;3种析出相的数密度分别为(29.1±6.14)×10^(10)、(1.42±0.29)×10^(10)、(2.15±0.99)×10^(10)个/m^(3)。NbC相尺寸最大,平均尺寸为3.0μm左右;TiN相和稀土氧化物尺寸接近,分别为2.0、1.5μm左右。液析第二相呈现多种核壳结构,如TiN-NbC和CeAlO_(3)-Al_(2)O_(3)双层结构、CeAlO_(3)-Al_(2)O_(3)-NbC三层结构、CeAlO_(3)-Al_(2)O_(3)-TiN-NbC四层结构。本文借助热力学计算和错配度理论阐明了各液析相的析出和核壳结构的形成机理,由于渣金反应和凝固时元素偏析,CeAlO_(3)、Al_(2)O_(3)、TiN和NbC在钢液中依次形成,各析出相界面之间具有一定的匹配性,液析第二相之间发生异质形核,促使形成了多种核壳结构。本文为理解和调控含稀土耐热钢的第二相提供了试验依据。展开更多
Noble metals have been widely used as heterogeneous catalysts because they exhibit high activity and selectivity for many reactions of both academic and industrial interest.The introduction of light atomic species(e.g...Noble metals have been widely used as heterogeneous catalysts because they exhibit high activity and selectivity for many reactions of both academic and industrial interest.The introduction of light atomic species(e.g.,H,B,C,and N)into noble metal lattices plays an important role in optimizing catalytic performance by modulating structural and electronic properties.In this review,we present a general overview of the recent advances in the modification of noble metals with light alloying elements for various catalytic reactions,particularly for energy‐related applications.We summarize the types,location,concentration,and ordering degree of light atoms as major factors in the performance of noble metal‐based catalysts,with emphasis on how they can be rationally controlled to promote activity and selectivity.We then summarize the synthetic strategies developed to incorporate light elements and highlight the theoretical and experimental methods for understanding the alloying effects.We further focus on the wide usage of noble metal‐based catalysts modified with different light alloying atoms and attempt to correlate the structural features with their catalytic performances.Finally,we discuss current challenges and future perspectives regarding the development of highly efficient noble metal‐based catalysts modified with light elements.展开更多
文摘铁素体/马氏体(ferrite/martensite,F/M)耐热钢中铌、钛等强碳化物形成元素容易在钢液凝固过程形成粗大的液析第二相,影响钢的蠕变和疲劳性能。调控液析第二相的成分和尺寸对提高钢的力学性能具有重要意义。电渣重熔和稀土改性都是调控钢中第二相的常用方法,两者共同作用对F/M耐热钢中液析第二相的影响缺乏相关研究。本研究旨在探究含铈的10Cr1Si F/M钢电渣重熔后第二相的析出特征。采用扫描电子显微镜(scanning electron microscope,SEM)和ASPEX自动扫描电镜等方法,对含铈的10Cr1Si钢电渣锭中的液相第二相进行统计分析。结果表明,电渣锭顶部、底部、中心、边缘不同位置中主要存在3类液相第二相,即黑色球状稀土氧化物CeAlO_(3)、多边形状氮化物TiN和针状、条状的碳化物NbC;3种析出相的数密度分别为(29.1±6.14)×10^(10)、(1.42±0.29)×10^(10)、(2.15±0.99)×10^(10)个/m^(3)。NbC相尺寸最大,平均尺寸为3.0μm左右;TiN相和稀土氧化物尺寸接近,分别为2.0、1.5μm左右。液析第二相呈现多种核壳结构,如TiN-NbC和CeAlO_(3)-Al_(2)O_(3)双层结构、CeAlO_(3)-Al_(2)O_(3)-NbC三层结构、CeAlO_(3)-Al_(2)O_(3)-TiN-NbC四层结构。本文借助热力学计算和错配度理论阐明了各液析相的析出和核壳结构的形成机理,由于渣金反应和凝固时元素偏析,CeAlO_(3)、Al_(2)O_(3)、TiN和NbC在钢液中依次形成,各析出相界面之间具有一定的匹配性,液析第二相之间发生异质形核,促使形成了多种核壳结构。本文为理解和调控含稀土耐热钢的第二相提供了试验依据。
文摘Noble metals have been widely used as heterogeneous catalysts because they exhibit high activity and selectivity for many reactions of both academic and industrial interest.The introduction of light atomic species(e.g.,H,B,C,and N)into noble metal lattices plays an important role in optimizing catalytic performance by modulating structural and electronic properties.In this review,we present a general overview of the recent advances in the modification of noble metals with light alloying elements for various catalytic reactions,particularly for energy‐related applications.We summarize the types,location,concentration,and ordering degree of light atoms as major factors in the performance of noble metal‐based catalysts,with emphasis on how they can be rationally controlled to promote activity and selectivity.We then summarize the synthetic strategies developed to incorporate light elements and highlight the theoretical and experimental methods for understanding the alloying effects.We further focus on the wide usage of noble metal‐based catalysts modified with different light alloying atoms and attempt to correlate the structural features with their catalytic performances.Finally,we discuss current challenges and future perspectives regarding the development of highly efficient noble metal‐based catalysts modified with light elements.
