Xiaoqiang Hu Namin Xiao Xinghong Luo Dianzhong Li
材料科学技术（英文）
Thermodynamic calculation, thermal analysis, and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program, differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer, respectively. Several critical phase transformation points were determined by combining experimental results with calculations. Two individually stable phases of Nb(C, N) and VN, instead of one single phase MX (X: C, N), M23C6 or Laves phases, were predicted in the calculated equilibrium phase diagram. An unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered steel. Two kinds of spherical Nb(C, N) with different size were recognized as the primary and the secondary precipitates of Nb(C, N) which contain different V contents. It was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb(C, N).
关键词:
Heat resistant steel
,
9-12%Cr steel
,
phase transformation
,
microstructure
,
MX precipitate
Xiaoqiang Hu Namin Xiao Xinghong Luo Dianzhong Li
材料科学技术（英文）
Thermodynamic calculation, thermal analysis, and identification and observation of precipitates have been carried out on a W-alloyed 10 wt pct Cr steel by means of ThermoCalc program, differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer, respectively. Several critical phase transformation points were determined by combining experimental results with calculations. Two individually stable phases of Nb(C, N) and VN, instead of one single phase MX (X: C, N), M23C6 or Laves phases, were predicted in the calculated equilibrium phase diagram. An unstable elongated M7C3 with relatively higher Cr was detected unexpectedly in the normalized and tempered steel. Two kinds of spherical Nb(C, N) with different size were recognized as the primary and the secondary precipitates of Nb(C, N) which contain different V contents. It was observed that one kind of complex precipitate in a special V-wing shape was resulted from two plate-like VN adhering to coarse primary spherical Nb(C, N).
关键词:
Heat resistant steel
,
9-12%Cr steel
,
phase transformation
,
microstructure
,
MX precipitate
毛立群
,
丁彦
,
张治军
,
党鸿辛
无机材料学报
采用sol-gel法制备纳晶TiO2薄膜,在溶胶的制备过程中加入丙烯酸对纳米TiO2胶体颗粒进行表面修饰.溶胶的透射电镜(TEM)分析表明,丙烯酸的表面修饰作用可以抑制在制备和陈放过程中胶体颗粒的团聚.采用原位程序升温,使用X射线衍射仪(XRD)对TiO2粉体由锐钛矿向金红石的转变过程(A→R)进行了考察,结果显示,晶粒的迅速生长和晶型的转变有着密切的联系;此外,丙烯酸的修饰作用能显著提高A→R的温度,且有助于抑制热处理过程中纳晶TiO2颗粒的团聚.TiO2薄膜的原子力显微照片(AFM)表明,丙烯酸修饰法制备的TiO2薄膜,膜层均匀连续,颗粒为纳米尺度.
关键词:
表面修饰
,
thermal aggregation
,
phase transformation
,
TiO2 thin film
芦玉峰
,
堵永国
,
肖加余
,
张为军
,
吴剑锋
,
杨光
,
王跃然
无机材料学报
doi:10.3724/SP.J.1077.2008.00159
用烧结法制备了化学计量比和高Ba含量的两组BaO-Al2O3-SiO2 (BAS)系微晶玻璃, 采用差示扫描量热法(DSC)和X射线衍射分析(XRD)等手段研究了ZrO2对BAS系微晶玻璃中六方钡长石析晶和六方钡长石向单斜钡长石晶型转变的影响. 研究表明, 两组BAS系玻璃的烧结温度低于850℃, 晶化温度低于900 ℃. 六方钡长石的析出为整体析晶. 不加形核剂晶型转变为整体析晶; 添加ZrO2晶型转变为表面析晶. 提高Ba含量或添加ZrO2促进六方钡长石的析出和晶粒细化. 化学计量比的BAS系微晶玻璃中添加ZrO2明显促进晶型转变. 高Ba含量的BAS系微晶玻璃中添加ZrO2表现为抑制晶型转变, 850℃保温100h不发生转变.
关键词:
微晶玻璃
,
celsian
,
low temperature sintering
,
crystallization
,
phase transformation
杨觉明
,
张立同
,
周万城
材料研究学报
用XRD、DTA、SEM、TEM和三点弯曲试验研究了溶胶一凝胶法合成的BAS(BaO·Al2O3·2SiO2)凝胶玻璃的结晶行为、晶型转变和热压BAS的显微结构与性能、结果表明,BAS凝胶玻璃在>1000℃时开始析晶,1100℃时完全晶化,结晶相为六方钡长石.不加成核剂,呈现整体结晶特性,晶粒小于1μm.加入50mg·g-1单斜钡长石作为晶种,可促进六方→单斜晶型转变.在1250℃处理7h,约有800mL·L-1六方钡长石转变为单斜钡长石.当存在莫来石时,材料的高温强度较高,其最大值出现在1200～1250℃复相BAS玻璃陶瓷的156MPa,204MPa和α=4.8×10-6/℃
关键词:
钡长石
,
feldspar
,
glass-ceramic
,
crystallization
,
phase transformation
李继光
,
孙旭东
,
茹红强
,
宋丹
,
孙祥云
,
李晓东
,
郝士明
材料研究学报
以Al(NO3)3和NH3水为原料制备Al(OH)3干凝胶,经煅烧合成了α-Al2O3纳米粉Al(OH)3干凝胶煅烧过程中的物相变化顺序为Al(OH)3→γ-AlOOH→γ-Al2O3→δ-Al2O3→θ-Al2O3→α-Al2O3.Al(OH)3凝胶中的NH4NO3显著降低γ、δ、θ及α-Al2O3的形成温度,其中α-Al2O3的形成温度降低50～100℃.2%α-Al2O3籽晶可使θ→α相变温度降低200℃.NH4NO3和籽晶共同作用可使θ→α相变在900℃完成,相变温度约降低300℃.获得的α-Al2O3,无明显团聚,粒度分布均匀,近似球形,平均粒径约为10nm.
关键词:
α-Al2O3
,
wet-chemical route
,
phase transformation
,
null
张明义陈铮王永欣卢艳丽张静范晓丽
金属学报
本文基于微观相场模型模拟了Ni75AlxV25-x(x=4.2, 5.0)合金中DO22(Ni3V)到L12 (Ni3Al)相变过程. 结合微观组织原子图像演化和界面处原子占位几率演化, 研究了异相间有序畴界的结构及其迁移特征, 提出了DO22 到L12相变过程的机制. 研究表明, L12与DO22相间存在5种界面, DO22 到L12相变过程中, 除了界面(002)D//(001)L之外, 其他4种界面都可以迁移; 在界面迁移过程中, 界面(100)D//(200)L和界面(100)D//(200)L?1/2[001]在迁移前后, 界面结构保持不变, 而界面(002)D//(002)L?1/2[100]迁移后形成界面(002)D//(002)L, 两者交替出现; 相变过程中, 界面迁移总是沿着最优化的路径进行原子跃迁和替换, 遵循跃迁原子数目最少、跃迁路径最短原则.
关键词:
Ni75AlxV25-x合金
,
phase transformation
,
odered domain interface
,
interface migration
,
microscopic phase–field
杨涛
,
王兴军
,
王辉
,
雷明凯
无机材料学报
采用溶胶-凝胶法(sol-gel)制备掺0～20mol％Er3+勃姆石(γ-AlOOH)凝胶,X射线衍射和差热分析法研究掺Er3+:γ-AlOOH凝胶在950～1400℃烧结的相变过程.结果表明:Er3+的掺杂降低α相的生长速度,抑制Al2O3的θ→α相变,推迟相变结束温度50～70℃.Er-Al-O系化合物Al10Er6O24和ErAlO3相的析出取决于掺Er~(3+)浓度和烧结温度.在较高烧结温度下,ErAlO3相由掺1～5mol％Er3+:Al2O3中析出;Al10Er6O24相则在掺5～20mol％Er3+:Al2O3中析出,随着烧结温度的升高,在全部掺Er3+:Al2O3中析出.ErAlO3相促进θ→α相变的形核,α相形核起始温度可提前30～50℃,但对α相生长影响不大.Al10Er6O24相对θ→α相变没有显著影响.
关键词:
勃姆石凝胶
,
Er3+ doping
,
phase transformation
,
sol-gel
