张立春
,
何安强
,
叶恒强
,
张永昌
材料研究学报
用HRTEM、TEM及EDAX分析研究了Al─Li—Cu—Mg—Zr合金中的一种新相(暂名H相)和六角Z相的结构,确定H相具有四方点阵,点阵参数为α=2.8nm,c=2.4nm,EDAX分析表明H相和Z相均含Al、Mg、Cu发现H相与Z相的共存取向关系为[100]‖[1120]Z,[1010]H‖[0001]Z。还观察到Z相中一种特有的旋转畴结构
关键词:
Al─Li─Cu─Mg─Zr合金.四方H相
,
tetragonal H phase
,
hexagonal Z phase
张立春
,
何安强
,
吴玉琨
,
叶恒强
,
张永昌
金属学报
利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成
关键词:
Al-Li-Cu-Mg-Zr合金
,
Z hexagonal phase
,
T f.c.c. phase
,
shear structure
Physical Review B
The Hamiltonian for a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab) = J(cd) not equal J(bc) = J(da)) was established. An extended Bogoliubov transformation was developed by solving an equation group, consisting of 20 equations and 20 unknowns. The procedure for solving the equation group was carried out by introducing a simple way of reducing the numbers of the equations and the unknowns. The spin-wave spectra in the present system have been determined by performing the standard Holstein-Primakoff transformation and the Bogoliubov one. It has been found that the spin-wave spectra of the present system depend on the exchange constants and that the degeneracy of the spin-wave spectra remains. The results for a special case (J(ab) = J(bc)) i.e., an antiferromagnet are discussed briefly. The spin-wave spectra of the four-sublattice Heisenberg antiferromagnet are found to be degenerative also and they are linear in k for small k.
关键词:
model
贾玉鑫
,
黄金亮
,
冯剑
材料热处理学报
采用Gleeble-1500D热模拟机对Mg-8Li-2Al-1Zn合金进行热压缩实验,研究了变形温度为523 ～ 723 K、应变速率为0.01 ～10 s-1条件下的合金热变形行为,并建立了合金的流变应力本构方程及热加工图.结果表明:Mg-8Li-2Al-1Zn合金的流变曲线均属于动态再结晶型,流变应力随着温度升高(应变速率降低)而减小.显微组织的变化验证了动态回复和动态再结晶的发生.Mg-8Li-2Al-1Zn合金流变应力本构关系可以用双曲正弦函数和Z参数准确的描述,平均应力指数为4.62,平均热激活能为139.35 J/mol.根据建立的加工图,预测合金热变形的最佳工艺参数为:523 ～573 K,0.1～1 s-1.
关键词:
镁锂合金
,
热变形
,
动态再结晶
,
本构方程
,
微观组织
Y.G. Cao
,
X.Y. Sun
金属学报(英文版)
J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.
关键词:
FRASTA
,
null
,
null
唐郑磊
,
张涛
,
杨东
,
李红洋
,
徐昭
,
庞林
钢铁研究
通过成分设计、轧制、热处理工艺设计,采用晶粒细化、固溶强化、析出强化等手段,对80、110mm的Q460GJC-Z35高强度钢板的研发工艺及过程进行试验设计。结果表明：通过Nb、V、Ti、Ni复合微合金化和控轧控冷、正火快冷（NAC）热处理相结合生产的模铸Q460GJE-Z35钢板具有晶粒细小、组织均匀,钢板屈服强度达到420~490 MPa,抗拉强度达到585~625 MPa,伸长率达到20%以上,0℃冲击功达到123 J以上,Z向断面收缩率大于35%,探伤达到1级探伤要求,实现了强度和韧性的良好匹配和较高的内部质量。
关键词:
Q460GJC-Z35
,
成分设计
,
热处理工艺设计
null
,
null
金属学报
在工程上,经常由于应力腐蚀开裂和氢脆引起中强度钢结构件发生滞后破坏。这类脆断往往从结构件中预先存在的疲劳或焊接裂纹处开始,因此,运用传统的光滑试样的检验方法不能反映这类破坏的特点。 本文将弹塑性断裂力学中的J积分概念用于滞后破坏的研究,提出用带预制疲劳裂纹的悬臂弯曲试样测定J积分的临界值J_(Ic)和应力腐蚀开裂阈值J_(Iscc)的方法。测定了40CrNiMo钢的J_(Ic)值及其在硫化氢水溶液中的J_(Iscc)值。通过和三点弯曲方法测定的J_(Ic)值的对比,以及和满足线弹性条件时直接测定的应力强度因子K_I值的对比,说明这种方法的可靠性。最后,对悬臂弯曲方法的特点进行了讨论。
关键词:
