马勤
,
余宁
,
康沫狂
,
杨延清
材料研究学报
利用行星式球磨机、X射线衍射仪和差热分析仪研究了Mo和Si元素混合粉末的机械合金化行为.结果表明,随着球磨时间的延长,Mo,Si混合粉末中首先形成Mo(Si)超过饱和固溶体,随后相继出现C40型h-MoSi2和Cllb型t—MoSi2纳米晶,最终的产物是以h—MoSi2纳米晶为主的非晶粉末混合物.
关键词:
Mo/Si固态相变
,
h-MoSi_2
,
t-MoSi_2
,
mechanical alloying
,
stacking fault
D Song
,
G.Y Zeng and X. Y Sun (Material Testing Centre
,
Northeastern University
,
Shenyang 110006
,
China Manuscript received 24 August 1995
,
in revised form 30 March 1996)
金属学报(英文版)
In the present paper, the microstructures of the two-phase alloy specimens of Ti-48AlMn-Nb, deformed at room temperature, 700℃and 900℃,have been investigated by using an EM400T transmission electron microscope. For specimens deformed at room temperature it is observed that (1/2) [011] superdislocation, normal (1/2) [110] dislocations, stacking fault band and a few twins etc. formed mainly in r-phase and a (1/2) [011] superdislocation preferentially decomposes into two partial dislocations with an antiphase boundary between them, which makes the dislocation difficult to move. The normal (1/2) [110] dislocations move with a long dragging tail behind them and have a low mobility In addition, the existence of a few twins implies a low mobility of (1/6) <112> twin dislocations, which leads to low plasticity of the allow. For samples deformed above 700℃,(1/2) [110] dislocations are in majority in the r-phase and exhibit short and bending dislocation segments without dragging tails,which may have resulted from an increased mobility of (1/2) [110] dislocations due to thermal activation. Meanwhile, (1/2) [011]superdislocation disappears, the mobility of (1/6)<112> dislocations is greatly increased, and thus a lot of twins are produced in r-phase. These make the plasticity of the alloy notably enhanced. The laminated structures in the alloy may be transformed into stacking fault bands during deformation at room temperature and the deformation above 700℃leads to the generation of a great quantity of twins.
关键词:
: dislocation
,
null
,
null
,
null
C.M Li
,
G.X. Dong
,
S.T- Dai
,
and D. Y Chen (Tsinghua University Beijing 100084
,
China)J Yin and D.X. Hu (Shanghai No.5 Steel Works
,
Shanghai 200940
,
China)
金属学报(英文版)
The interior structural evolution accompanying reverse shape memory effect (RSMEin a Cu-Zn-Al alloy was studied by means of transmission electron microscopy. It was found that RSME is closely related to bainitic transformation in this alloy during the isothermal reaction at moderate temperatures. At a given temperature and a certain external constraint stress, the shape memory effect depends mainly on the aging time.During the early stage, the shape memory effect enhances with the increase of reactiotn time. Then it will decrease gradually apon further aging. If the alloy is overaged, the stacking faults of bainite will disappear gradually by the motion of partial dislocations through which long range diffusion of solute atoms takes place, giving rise to the deterioration of RSME. When all the bainite transforms to α phase, RSME will lose completely.
关键词:
reverse shape memory effect
,
null
,
null
,
null
