CHEN Niug
,
YU Zongsen University of Science and Technology Beijing
,
Beijing
,
China professor
,
Department of Materials Physics
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
Si segregation was observed in the vacancy condensation pits,formed by supersaturated vacancies beneath the oxidation layer of Al-0.35wt-%Si alloy,by optical microscopy,X- ray photoelectron spectroscopy and microhardness tests.This phenomenon could only be explained by vacancy-Si complex inducing non-equilibrium segregation.
关键词:
non-equilibrium segregation
,
null
,
null
,
null
,
null
王凯
,
王民庆
,
徐庭栋
材料科学与工艺
为确定304L钢中P的偏聚特征,分析了Briam在俄歇能谱(AES)下得到的磷晶界偏聚浓度.研究表明,经1100℃固溶1 h、水淬后的304L不锈钢,不仅在700℃恒温时效过程中出现磷的晶界偏聚浓度峰值,并在500、550、600、650、700℃分别恒温时效100 h后,600℃处发现磷的晶界偏聚浓度峰值.分析发现,磷在304L钢中发生了非平衡晶界偏聚.通过对磷非平衡晶界偏聚恒温动力学特征的讨论,提出了回火脆性的非平衡晶界偏聚机理.
关键词:
晶界
,
非平衡偏聚
,
磷
,
304L不锈钢
,
回火脆性
花晓燕
,
郭长庆
,
韩继炜
,
石安君
材料热处理学报
介绍了将Fe-Cr-B合金1050℃×30 min奥氏体化后经水冷、空冷和炉冷3种不同的冷却速度处理后对其显微组织和韧性的影响.采用光学显微镜、SEM、EDS和XRD对热处理后的组织进行了观察和分析.结果表明,奥氏体化后不同的冷却速度对基体组织的形貌没有产生明显的影响,并且,在晶界上呈连续分布的、粗大的网状硼化物也只是出现了局部断裂,边缘变得更加圆整.然而,冷却速度的变化对于基体上分布的析出相颗粒却有着显著的影响.随着冷却速度的下降,基体上析出相颗粒的数量逐渐增多、部分颗粒尺寸增大,并且,分布的不均匀性也在逐渐加强.其具体表现形式为:新析出相颗粒倾向于沿着在晶粒内部已经由析出相颗粒密集析出而形成的亚晶界或亚相界上优先析出.从而,使得这些部位逐渐由一根线条扩大为一个区域,这样的组织现象与Fe-C合金中析出相颗粒的析出规律是不相同的.XRD检测表明:这些析出相颗粒为M23 (C,B)6和M6(C,B).与Fe-C合金不同的是:Fe-Cr-B合金的韧性随奥氏体化后冷却速度的升高而增大,但增大的幅度不大.
关键词:
Fe-Cr-B合金
,
冷却速度
,
显微组织
,
析出相
,
非平衡偏聚
CHU Youyi ZHANG Sanhong HE Xinlai KE Jun(T.Ko) University of Science and Technology Beijing
,
China CHU Youyi Professor
,
The Nonferrous Metals Society of China
,
Room 602
,
B12
,
Fuxing Road
,
Beijing 100814
,
China
金属学报(英文版)
In consideration of the local equilibrium among vacancies,solute atoms and vacancy-solute atom complexes and the influence of equilibrium grain boundary segregation,theoretical dy- namic formulas for non-equilibrium grain boundary segregation of solute have been derived on the basis of the vacancy-dragging mechanism.Theoretical calculation by computer has been carried out for the non-equilibrium segregation of boron to austenitic grain boundaries during isothermal holding and continuous cooling after heating at high temperatures.The re- suits agree well with those obtained from experiments.
关键词:
solute
,
null
,
null
,
null
YU Zongsen CHEN Ning University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
Mechanism for diffusion of B in γ-Fe is believed to be mainly by means of boron-vacancy complexes other than as interstitial atoms previously.This was made of calculation on the ba- sis of theoretical model proposed by the authors.The calculated diffusion coefficient of B in γ-Fe after this mechanism is consistent with the experimental values.In addition,this is also supported by the non-equilibrium segregation phenomenon of B at grain boundaries of γ-Fe and the lattice constant measurement of Fe-B alloy.
关键词:
boron
,
null
,
null
,
null
,
null
P. Wu
金属学报(英文版)
The development of non-equilibrium segregation of boron at grain boundaries in Fe-40%Ni alloy during continuous cooling process was experimentally observed with boronParticle Tracking Autoradiography (PTA) and Transmission Electron Microscopy(TEM). The samples with 10ppm boron were cooled at 2℃/s to 1040, 980, 920,860, 780 and 640℃ respectively after pre-heat treatment of 1150℃ for 15min witha Gleeble-1500 heat simulating machine, then water quenched to room temperature.The width of segregation layer and boron depletion zone, rich factor and other pc-rameters were measured by a special image analysis system. The experimental resultsof PTA show that the grain boundary segregation of boron during cooling process is adynamic process and the development of the non-equilibrium segregation experiencesthree stages: first increases rapidly from 1150 to 1040℃, then gently from 1040 to860℃, and rapidly again from 860℃ to 640℃. The width of boron depletion zoneincreases from about 11μm at 1040℃ to 26μm at 640℃. TEM observation showsthat boron precipitates exist at grain boundaries when the samples are cooled to below860℃. The experimental phenomena are briefly discussed.
关键词:
boron
,
null
,
null
