SUN Baode
,
CHE Xiaozhou
,
LIN Dongliang
,
ZHOU Yaohe(Department of Materials Engineering
,
Shanghai Jiaotong University
,
Shanghai 20030
,
China)(Department of Materials Science
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China)
金属学报(英文版)
The morphology and structure of melt spinning Ni-33.6at% Al doped with B and RE were investigated.The results show that the alloy consists of L10 martensitic grains and L12 Ni3Al at the grain boundaries when it contains no B and RE.The addition of 0.11-0.31wt% B can suppress the martensitic transformation and Ni3Al separation at the boundaries,and a supersaturated B2 single phase NiAl is obtained.The addition of 0.05wt% RE can eliminate Ni3Al precipitated at the boundaries and get complete martensite,but 0.2-0.8wt% RE addition can suppress the martensitic transformation, and supersaturated B2 single phase NiAl is obtained.The formation mechanism of supersaturated B2 single phase NiAl has been analyzed.
关键词:
:NiAl
,
null
,
null
,
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LIN Dongliang
,
(T.L.Lin)
,
CHEN Da Shanghai Jiaotong University
,
Shanghai
,
China Professor
,
Dept.of Materials Science
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China
金属学报(英文版)
The deformation behaviours of Ni_3Al alloys with various chemical compositions and subjected to different heat treatments were in situ observed under SEM. Moreover,in situ observations of slip trace were supplemented by the direct observation of dislocation arrangements under TEM.In B-doped Ni_3Al alloys it is shown that close to the grain boundary there exists a thin slip transition region,within which slip lines are reoriented or other slip systems are operated to produce a local strain accommodation and to relax the stress concentration at grain bound- aries.Boron seems to lower the stress for dislocation generation from the grain boundaries or to ease the cross-slip close to the boundaries,and also to increase the number of dislocation sources.However,B-enhenced ductility is seriously affected by stoichiometry,the addition of a tertiary alloy element and heat treatment,etc..
关键词:
Ni_3Al
,
null
,
null
,
null
,
null
LIN Dongliang
,
(T.L.Lin)
,
CHEN Da Shanghai Jiaotong University
,
Shanghai
,
China Professor
,
Dept.of Materials Science
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China
金属学报(英文版)
The embedded atom type potentials and static relaxation method combined with steepest gra- dient computational technique have been used to simulate the grain boundary cohesive ener- gies,the distribution of electron density and stress field in the grain boundary,region,and oth- er related problems of[100],[110]and[111]symmetric tilt grain boundaries in Ni_3Al with different grain boundary geometrical index and composition.Their relations with the segrega- tion or boron,behaviors or the grain boundary,and especially the stoichiometrical effect of B induced ductility have also been studied and discussed.
关键词:
Ni_3Al
,
null
,
null
,
null
