G.S.Cho
,
K.H.Choe
,
K.W.Lee
,
A.Ikenaga
,
null
,
null
,
null
,
null
,
null
,
null
,
null
材料科学技术（英文）
The effects of alloying elements on the as-cast microstructures and mechanical properties of heavy section ductile cast iron were investigated to develop press die material having high strength and high ductility. Measurements of ultimate tensile strength, 0.2% proof strength, elongation and unnotched Charpy impact energy are presented as a function of alloy amounts within 0.25 to 0.75 wt pct range. Hardness is measured on the broken tensile specimens. The small additions of Mo, Cu, Ni and Cr changed the as-cast mechanical properties owing to the different as-cast matrix microstructures. The ferrite matrix of Mo and Ni alloyed cast iron exhibits low strength and hardness as well as high elongation and impact energy. The increase in Mo and Ni contents developed some fractions of pearlite structures near the austenite eutectic cell boundaries, which caused the elongation and impact energy to drop in a small range. Adding Cu and Cr elements rapidly changed the ferrite matrix into pearlite matrix, so strength and hardness were significantly increased. As more Mo and Cr were added, the size and fraction of primary carbides in the eutectic cell boundaries increased through the segregation of these elements into the intercellular boundaries.
关键词:
Heavy section ductile cast iron
,
null
,
null
A.Ikenaga
,
G.S.Cho
,
K.H.Choe
,
K.W.Lee
材料科学技术（英文）
During the EPC (expendable pattern casting) process, one of the essential requirements is to prevent pattern distortion during sand filling and compaction. A new method which vibrates the system in a two-dimensional circular mode has been applied to the EPC process. The molding properties of unbonded sand obtained by this new vibration mode are investigated and compared with those in the one-dimensional vertical mode. For adequate compaction of sand, the circular vibration mode is more effective than the vertical mode. Sand became more fluidized by the circular vibration and the particle pressure coefficient was close to unity. The particle pressure coefficient, which is defined as the ratio of horizontal to vertical sand pressure, is responsible for the effectiveness of sand filling.
关键词:
EPC process
,
null
,
null
,
null
,
null
G.S.Cho
,
J.H.Yang
,
K.H.Choe
,
K.W.Lee
,
A.Ikenaga
材料科学技术（英文）
We focused on the surface reinforcement of ligth weight casting alloys with Ni-Al intermetallic compounds by in-situ combustion reaction to improve the surface properties of non-ferrous casting components. In our previous works, green compact of elemental Ni and Al powders were reacted to form Ni3Al intermetallic compound by SHS (Self-propagating high temperature synthesis) reaction with the heat of molten Al alloy and simultaneously bonded with Al casting alloy. But some defects such as tiny cracks and porosities were remained in the reacted compact. So we applied pressure to prevent thermal cracks and fill up the pores with liquid Al alloy by squeeze casting process. The compressed Al alloy bonded with the Ni3Al intermetallic compound was sectioned and observed by optical microscopy and scanning electron microscopy (SEM). The stoichiometric compositions of the intermetallics formed around the bonded interface and in the reacted compact were identified by energy dispersive spectroscopy (EDS) and electron probe micro analysis (EPMA). Si rich layer was formed on the Al alloy side near the bonded interface by the sequential solidification of Al alloy. The porosities observed in the reacted Ni3Al compact were filled up with the liquid Al alloy. The Si particles from the molten Al alloy were detected in the pores of reacted Ni3Al intermetallic compact. The Al casting alloy and Ni3Al intermetallic compound were joined very soundly by applying pressure to the liquid Al alloy.
关键词:
Joining
,
null
,
null
,
null
,
null
陆安慧
,
郑经堂
,
王茂章
,
樊彦贞
新型炭材料
doi:10.3969/j.issn.1007-8827.2000.01.005
ACFs的吸附性能主要取决于比表面积和孔隙结构,在不同相对压力下的吸附行为对应不同的孔隙结构.在一定范围内微孔是决定吸附能力大小的重要因素.以N2吸附等温线为依据,采用H-K法考察了不同比表面积ACFs在微观结构以及吸附性能上的差异.采用BET法计算比表面积,Hovath-Kawazoe方程表征微结构.研究表明ACFs含有大量的小于0.7 nm的极微孔,这些极微孔对吸附等温线的贡献较大,并且在吸附过程中赋予ACFs分子筛特性.同时发现随着ACFs比表面积的增加极微孔的分布相应变宽.
关键词:
表面积
,
吸附等温线
,
极微孔
,
孔分布
Materials Characterization
Dendritic coarsening of gamma' was investigated in a directionally solidified Ni-base superalloy during exposure at 1173 K for 24,000 h. Chemical homogeneity along different directions and residual internal strain in the experimental superalloy were measured by electronic probe microanalysis (EPMA) and electron back-scattered diffraction (EBSD) technique. It was indicated that the gradient of element distribution was anisotropic and the inner strain between dendrite core and interdendritic regions was different even after 24,000 h of exposure at 1173 K, which influenced the kinetics for the dendrite coarsening of gamma' phase. (C) 2010 Elsevier Inc. All rights reserved
关键词:
Superalloy;Coarsening;Exposure;Segregation;ni-base superalloy;evolution;field
罗将
,
潘世烈
,
韩健
人工晶体学报
采用室温溶液法生长K2CaB8O26H24晶体,并得到尺寸为11mm×6 mm×5 mm的单晶.该晶体属于正交晶系,P212121空间群,晶胞参数为a＝1.15520(2)nm,b＝1.24751(3)nm,c＝1.65768(4)nm.红外光谱测量证实晶体结构中含有BO33-和BO54-基团.透过光谱表明K2CaB8O26H24晶体紫外吸收边在200nm左右.K2CaBsO26H24晶体粉末倍频效应(SHG)测试表明该化合物具有倍频效应,信号强度约为KH2PO4晶体的0.3倍.
关键词:
室温溶液法
,
K2CaB8O26H24
,
倍频
张松
,
袁广银
,
卢晨
,
丁文江
金属学报
doi:10.3724/SP.J.1037.2010.00177
采用金属型铸造和慢速凝固,在不同冷却速率下制备了Mg-10Gd-3Y-1.8Zn-0.5Zr(质量分数,%)(GWZ1032K)合金.采用SEM,TEM和XRD研究了冷却速率不同的GWZ1032K合金的组织和相构成.在GWZ1032K合金中,α-Mg基体中的层片状14H-LPSO结构随着冷却速率的下降而增加,在冷却速率为0.005℃/s的试样中充满了整个晶粒;随着合金冷却速率降低,GWZ1032K合金中晶界第二相分别由5℃/s时的(Mg,Zn)3RE相转变为0.5和0.1℃/s时的(Mg,Zn)3RE相和14H-LPSO结构的X相共存;在0.01和0.005℃/s时只有14H-LPSO结构的X相.结果显示在接近于平衡凝固的缓慢冷速条件下,更容易形成具有稳定结构的层片状14H-LPSO结构和X相.在冷却速率为0.5和0.1℃/s时,(Mg,Zn)3RE共晶相和X相共存,(Mg,Zn)3RE共晶相和X相的位向关系为[110]xphase//[(2)23](Mg,Zn)3RE和∠g(001)xphase g(110)(Mg,Zn)3RE=8.4°.
关键词:
14H-LPSO结构
,
冷却速率
,
Mg-Gd-Y-Zn合金
,
X相
刘舟
,
曾英
,
于旭东
稀有金属
doi:10.3969/j.issn.0258-7076.2013.01.019
采用等温溶解平衡法研究了三元体系Rb+∥Cl-,borate-H2O 348 K时的稳定相关系.测定了该三元体系348 K时的平衡液相组成和主要物化性质(密度、折光率).根据实验数据绘制了相应的等温溶解度图,物化性质-组成图.研究发现:该体系属于简单共饱型,无复盐或固溶体形成.相图含有1个共饱点,2条溶解度单变量曲线以及2个单盐结晶相区,分别对应RbCl和RbB5O8 ·4H2O结晶区.该体系RbCl结晶区面积小,溶解度大;RbB5O8 ·4H2O结晶区面积大,溶解度小.平衡液相的密度和折光率随着RbCl含量的增大而增大,在共饱点E处达到最大值.
关键词:
溶解度
,
相平衡
,
铷
,
硼酸盐
陈义平
,
张汉辉
,
黄长沧
,
杨齐瑜
,
孙瑞卿
功能材料
采用水热法合成了[H(4,4'-bpy)]2[K2Mo8O26],X-ray单晶结构解析表明:该化合物属三斜晶系,空间群:P-1,晶胞参数:a=0.78029(8)nm,b=0.98715(8)nm,c=1.32438(6)nm,α=99.383(3),β=102.0600(19),γ=108.090(2),β-[Mo8O26]单元通过部分端氧原子与K原子相连成层状,4,4'-联吡啶中质子化的N原子与非质子化的N原子通过氢键联成链状,链与链之间通过π-π堆垛成层状结构.
关键词:
水热合成
,
钼酸盐
,
钾
,
晶体结构
张松袁广银卢晨丁文江
金属学报
doi:10.3724/SP.J.1037.2010.00177
采用金属型铸造和慢速凝固, 在不同冷却速率下制备了Mg-10Gd-3Y-1.8Zn-0.5Zr(质量分数, %) (GWZ1032K)合金. 采用SEM, TEM和XRD研究了冷却速率不同的GWZ1032K 合金的组织和相构成. 在GWZ1032K合金中, α-Mg基体中的层片状14H-LPSO结构随着冷却速率的下降而增加, 在冷却速率为0.005℃/s的试样中充满了整个晶粒;随着合金冷却速率降低, GWZ1032K合金中晶界第二相分别由5℃/s时的(Mg, Zn)3RE相转变为0.5 和0.1℃/s时的(Mg, Zn)3RE相和14H-LPSO结构的χ相共存;在0.01和0.005℃/s时只有14H-LPSO结构的$\chi$相. 结果显示在接近于平衡凝固的缓慢冷速条件下, 更容易形成具有稳定结构的层片状14H-LPSO结构和χ相.在冷却速率为0.5和0.1℃/s时, (Mg, Zn)3RE共晶相和χ相共存, (Mg, Zn)3RE共晶相和χ相的位向关系为 [110]χ phase//[223](Mg, Zn)3RE和∠g(001)χ phase g(110) (Mg, Zn)3RE=8.4°.
关键词:
14H-LPSO结构
,
solidification rate
,
Mg-Gd-Y-Zn alloy
,
χ phase
