Sheng Li
,
Yu-Zeng Chen
,
Yu-Ke Cao
,
Feng Liu
金属学报(英文版)
doi:10.1007/s40195-016-0367-4
It is well known that, in kinetics, the interaction between dislocations and interstitial solute normally exerts strong solute drag effect on dislocations, leading to strong solution hardening of the metals. However, due to the low mobility of interstitial solute in many metals, thermodynamic aspect of the interaction between dislocations and interstitial solute is often unobservable and omitted. It will be shown in this article by reviewing the H-induced behaviors in metal-H systems, especially the recent progress in Pd-H system that, when the interstitial solute atoms are highly mobile and able to collect in the vicinity of mobile dislocations easily, the scenario will be remarkably different. The interaction between dislocations and these highly mobile interstitial solute atoms, in thermodynamics, will reduce the line energy of dislocations and will facilitate the generation of dislocations, leading to an increase in dislocation density and an enhanced strain hardening of metals upon plastic deformation.
关键词:
Plastic
,
deformation
,
Dislocation
,
Interstitial
,
solute
,
Strengthening
,
mechanism
,
Thermodynamics
Weimin MAO
,
Dong LI
材料科学技术（英）
The image stress of straight screw dislocations parallel to the medium surface covered by thin heterogeneous films was analyzed and deduced, in order to calculate the image shear stress. The relationship between image stress and distance from the screw dislocation to the interface of pure aluminum and its oxide covering was calculated based on the analysis. It was shown quantitatively that a sign conversion of the image stress appears in the case of thin oxide covering, while dislocation would pile up near the interface because of the possible slips of the screw dislocations induced by the image stress, which might break down the very thin oxide covering. Further investigation on edge dislocations or other dislocation configurations need to be done.
关键词:
Dislocation
,
null
,
null
,
null
,
null
,
null
,
null
Shaohua Zhang
材料科学技术（英）
The stress rupture properties of a single crystal superalloy were tested at 975°C/255MPa as a function of the deviation degrees from [001]. The misorientation of the specimens away from [001] distributed approximately along a line between [001]-[011] and [001]-[-111] boundaries in the triangle of the stereographic projection. Creep rupture lifetimes of the specimens were not sensitive to the misorientation until the deviation degree exceeded ~30°. Two steps of lattice rotation were found in all specimens during creep, first towards the [001]-[-111] boundary, and then to [001] or [-111] along the boundary. Single slip and strong asymmetric deformation were observed during the first stage of lattice rotation in specimens with large misorientation. The rotation mechanism was associated with the activated slip systems according to the calculated Schmid factors. The impact of lattice rotation on the rupture properties was also discussed.
关键词:
Dislocation
Yuli GU
金属学报(英文版)
Thermo-mechanical fatigue (TMF) behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550℃ to 720℃. The results show that TMF fracture mode is intergranular for the in-phase (IP), but transgranular cleavage-like for the out-of-phase (OP) samples. The total content of Al, Ti and Nb in the γ' phases for the IP or OP samples and the partitioning ratio of γ'/γ in these elements for the IP samples are relatively higher at the lower strain amplitude, which is consistent with the case of the γ' size that is larger at the lower strain amplitude, the lattice parameter misfit is negative and the absolute value is lower at the lower strain amplitude that is correlative with the change of the γ' morphology. The deformation at the lower strain amplitude is mainly dominated by the dislocation lines and dislocation pairs in the matrix channels, at the higher strain amplitude dominated by the large numbers of superlattice stacking faults within the γ' phases.
关键词:
Nickel-base superalloy
,
thermo-mechanical fatigue
,
elemental partitioning
,
γ′ size
,
dislocation （镍基高温合金
,
热机械疲劳
,
元素分配
,
γ′尺寸
,
位错）
Hao YU
,
Hao REN
,
Yonglin KANG
,
Kelu WANG
材料科学技术（英）
Two experiments were carried out on the same compact strip production (CSP) line, which differs in that one of them experienced γ→α→γ﹡thermal history. The differences in microstructure, precipitation, misorientation etc between two experiments were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD) and positron annihilation technique (PAT). The carbon concentration in matrix is more inhomogeneous in the experiment than that withγ→α→γ﹡ thermal history. The specific precipitation characteristic in the experiment withoutγ→α→γ﹡ thermal history is discussed on the basis of different carbon diffusion behavior and interaction between dislocation and excess carbon.
关键词:
Compact strip production
,
null
,
null
,
null
,
null
沈贇靓
,
闵娜
,
谢尘
,
吴晓春
上海金属
利用XRD、高分辨透射电镜等试验方法,结合内耗法研究深冷处理对80Cr9Mo2钢回火特性影响.结果表明:深冷处理前低温回火将导致部分碳原子由马氏体相扩散至残留奥氏体相中,提高残留奥氏体稳定性.而回火前深冷处理将导致更多残留奥氏体相变为低温马氏体,马氏体相(包括低温马氏体相)含量增加,可动位错密度提高,位错处偏聚间隙碳原子含量提高.有利于回火过程中析出更多数量的细小碳化物,这是深冷处理提高耐磨性能的主要原因.
关键词:
80Cr9Mo2钢
,
深冷处理
,
残留奥氏体
,
马氏体
,
位错
,
内耗
李文涛
,
林振铭
,
汪宏斌
,
陈卓
,
金曼
上海金属
冷轧带钢中的残余应力不均匀分布是影响带钢板形的根本原因.去应力退火处理是消除残余应力的常用方法.结合带钢生产工艺,利用X射线衍射技术研究了低碳冷轧带钢在退火处理过程中的残余应力的变化情况.研究发现,在200～ 300℃退火,残余应力剩余百分比为80％,在400℃及以上温度退火,残余应力基本消除.通过结合微观组织、硬度以及电阻率的变化,揭示了残余应力主要通过晶粒内部位错的抵消和重新排布降低畸变能来去除.
关键词:
冷轧带钢
,
残余应力
,
位错
,
退火
