费广涛
,
朱震刚
材料研究学报
本文研究了多晶99.999wt-%Al 在拉压疲劳早期阶段中应力、内耗、超声衰减随循环圈数的变化关系,以及它们与试样内部位错组态的联系。实验结果表明,当超声衰减达到最大值时,对应的位错组态为缠结带与单根位错并存,当应力达到最大值时,对应的位错组态为胞状结构。
关键词:
疲劳
,
stress
,
dislocation configuration
,
internal friction
,
ultrasonic attenuation
黄俊
,
李慧
,
王执锐
,
吴玉程
机械工程材料
对单相体心立方近β钛合金在不同加载应力以及循环周次下进行压缩疲劳试验,对循环过程中的范性应变机制进行分析,通过研究滑移模式、显微组织演化等对早期微裂纹萌生的影响以及观察疲劳前后位错组态的演化,分析了循环形变特征与表面滑移模式之间的内在联系.结果表明:单相近β钛合金经纯压缩循环形变后出现出典型的平面滑移特征以及表面应力集中现象,循环形变后的位错湮灭、退孪晶和孪晶界结构简化造成的局部应力改变是导致应力集中滑移带出现以及平面滑移机制的重要因素.
关键词:
近β钛合金
,
压缩疲劳试验
,
循环形变
,
平面滑移
,
位错演化
潘昆明
,
张来启
,
王礞
,
林均品
金属学报
doi:10.3724/SP.J.1037.2013.00410
采用压缩和单边缺口三点弯曲实验,研究了MosSiB2 (T2相)合金试样在真空条件和不同温度下的压缩行为和断裂行为,利用XRD,SEM-EDS和TEM等对试样变形后的微观组织、位错组态和断口形貌进行了分析和观察.结果表明,T2相的脆-韧转变温度为1000---1200℃.在外加切应力的作用下,[010](001)和〈110〉{110}等多个滑移系开始开动,导致试样发生明显的塑性变形.由于刃型位错比螺型位错或混合型位错活跃,表现为[010]刃型位错深入到滑移面{110},与〈110〉位错发生交互作用,形成大量位错节点,导致加工硬化.随温度升高,试样断裂模式从单一解理断裂向穿晶解理-沿晶混合断裂转变,在1000℃时,试样断口处能清晰地观察到滑移带.
关键词:
Mo5SiB2(T2相)
,
压缩变形
,
断裂
,
位错组态
,
脆-韧转变
宋衎
,
喻凯
,
林鑫
,
陈静
,
杨海欧
,
黄卫东
金属学报
doi:10.11900/0412.1961.2014.00648
研究了经过高温均匀化固溶处理+中间δ时效处理+双级时效处理的激光立体成形Inconel 718合金的组织及力学性能,并考察了热处理后合金的位错组态.结果表明,由于热处理过程中的再结晶行为,合金组织由沉积态的初始柱状晶转化为等轴晶.Laves相完全固溶,针状δ相以及γ"强化相分别在晶界处以及γ基体上大量弥散析出.激光立体成形Inconel 718合金热处理态的抗拉强度、屈服强度、延伸率以及断面收缩率均达到锻件标准.位错与γ"相的相互作用为位错切割γ"相以及位错绕过γ"相,在位错绕过γ"相的区域,位错密度比位错切割γ"相区域高.由于热处理态δ相尺寸大于锻件,位错会在δ相中发生塞积.碳化物和位错之间也存在强烈的相互作用,通过钉扎和拖曳作用来阻碍位错运动.
关键词:
激光立体成形
,
Inconel 718
,
显微组织
,
力学性能
,
位错组态
YAO Kefu TANG Naiyong CHEN Nanping Tsinghua University
,
Beijing
,
China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A213—A218
,
Ph.D.Student
,
Dept.of Materials Sci.and Eng.
,
Tsinghua University
,
Beijing
,
China
金属学报(英文版)
The development of dislocation structures in the plastic zone ahead of a crack tip has been in- vestigated in a duplex stainless steel during in-situ deformation experiments in a scanning transmission electron microscope.It was found that the dislocation distribution was significantly different in the ferrite and in the austenite.In the ferrite grains,the dislocations emitted by the crack tip may cross-slip out of the original slip planes and form a broad plastic zone.However,in the austenite,the dislocation free zone is small and the dislocations emitted by the crack pile up in its slip plane.The selection of slip systems at the crack tip depends on the crack tip Schmid factors in both phases.But after large deformation,the selection of the second slip systems at the craek tip in austenite does not depend on the Schmid factors.
关键词:
crack tip
,
null
,
null
,
null
CHAI Huifen WANG Liqin Xi'an Jiaotong Uuiversity
,
Xi'an
,
ChinaLAIRD Campell University of Pennsylvania
,
U.S.A.[Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A201—A206
,
Associate professor
,
Xi'an Jiaotong University
,
Xi'an
,
China
金属学报(英文版)
The evolution of dislocation structures in 6% prestrained steel 1018 during fatigue has been studied by TEM.The dislocations are quite movable,the loose cells quickly change to “checkboard”structures,in which the main cell walls lie about {100}.Then,the low energy dislocation structures i.e.dipolar walls and abyrinth structures are evolved.The characteristic of labyrinth and the orientation of dipolar walls are quite similar to fcc crystal.This indicates the energy state of system and the moving ability of dislocations are important factors affect- ing softening process,rather than the slip geometric characteristic of dislocations and details of dislocations.The decreasing in misorientation between adjoining cells and internal stress are discussed.
关键词:
steel 1018
,
null
,
null
