Volume 0,Issue 3,2000 Table of Contents
2000(3).
Abstract:
An advanced method of producing Al 3Ti/Al composites, self propagating high temperature synthesis (SHS) in an Al melt, is described. The mole ratio of Al/Ti in the starting powder mixture is an important parameter for that controls the microstructure of the Al 3Ti compound produced by SHS. When Al/Ti is much smaller than 3/1(the stoichiometric ratio), large needle like Al 3Ti structures will be produced. When Al/Ti is close to or larger than this value, the more favorable homogeneously distributed blocky Al 3Ti will be obtained. But if Al/Ti ratio is larger than 3 75/1, the SHS process will stop because more heat is consumed for heating up and melting the Al powder.
An advanced method of producing Al 3Ti/Al composites, self propagating high temperature synthesis (SHS) in an Al melt, is described. The mole ratio of Al/Ti in the starting powder mixture is an important parameter for that controls the microstructure of the Al 3Ti compound produced by SHS. When Al/Ti is much smaller than 3/1(the stoichiometric ratio), large needle like Al 3Ti structures will be produced. When Al/Ti is close to or larger than this value, the more favorable homogeneously distributed blocky Al 3Ti will be obtained. But if Al/Ti ratio is larger than 3 75/1, the SHS process will stop because more heat is consumed for heating up and melting the Al powder.
2000(3).
Abstract:
Microstructural variation in sputtered Ni 9 7Cr 5 5Al 7Ti (wt%) nanocrystalline coatings during high temperature oxidation was observed. The formation of TiO 2 on sputtered Ni Cr Al Ti coatings (or the sputtered coatings removed oxide coating after 90 min oxidation) have been investigated. It was found that the formation and TiO 2 of growth are closely related to the pricipitation of Ni 3(AlTi) phase. These effects are also discussed in detail
Microstructural variation in sputtered Ni 9 7Cr 5 5Al 7Ti (wt%) nanocrystalline coatings during high temperature oxidation was observed. The formation of TiO 2 on sputtered Ni Cr Al Ti coatings (or the sputtered coatings removed oxide coating after 90 min oxidation) have been investigated. It was found that the formation and TiO 2 of growth are closely related to the pricipitation of Ni 3(AlTi) phase. These effects are also discussed in detail
2000(3).
Abstract:
MoSi 2 WSi 2 powders have been synthesized by means of self propagating high temperature combustion. It was found that not only MoSi 2 WSi 2 but also Mo 5Si 3 W 5Si 3 can be synthesized by this method when suitable ratios of Mo, W and Si powders were used. As the W content increases, the adiabatic temperature of reactive system decreases, which influences the synthesis process. It is also confirmed that MoSi 2 WSi 2 and Mo 5Si 3 W 5Si 3 exist as solid solutions of [Mo (1-x) ,W x]Si 2 and [Mo (1-y) ,W y] 5Si 3, respectively.
MoSi 2 WSi 2 powders have been synthesized by means of self propagating high temperature combustion. It was found that not only MoSi 2 WSi 2 but also Mo 5Si 3 W 5Si 3 can be synthesized by this method when suitable ratios of Mo, W and Si powders were used. As the W content increases, the adiabatic temperature of reactive system decreases, which influences the synthesis process. It is also confirmed that MoSi 2 WSi 2 and Mo 5Si 3 W 5Si 3 exist as solid solutions of [Mo (1-x) ,W x]Si 2 and [Mo (1-y) ,W y] 5Si 3, respectively.
Dong Xiangting
,
Liu Guixia
,
Zhang Wei
,
Wang Dayu Lu Yanhong
,
Liu Jinghe
,
Lu Jianli
,
Hong Guangyan
2000(3).
Abstract:
Nanocrystalline SnO 2 with different particle sizes has been prepared by means of hydrothermal precipitation. The resulting SnO 2 nanometer size powders, which are basically spherical in shape according to TEM, are tetragonal in structure with space group P4/mnm. Calculation shows that the crystallite size of SnO 2 increases with increase of the calcination temperature, but that the average crystal lattice distortion rate decreases with increase of crystallite size. The smaller the particle, the bigger the crystal lattice distortion and the slower the crystal growth rate. Weight loss analysis indicates the prepared SnO_2 is very slightly impure.
Nanocrystalline SnO 2 with different particle sizes has been prepared by means of hydrothermal precipitation. The resulting SnO 2 nanometer size powders, which are basically spherical in shape according to TEM, are tetragonal in structure with space group P4/mnm. Calculation shows that the crystallite size of SnO 2 increases with increase of the calcination temperature, but that the average crystal lattice distortion rate decreases with increase of crystallite size. The smaller the particle, the bigger the crystal lattice distortion and the slower the crystal growth rate. Weight loss analysis indicates the prepared SnO_2 is very slightly impure.
2000(3):149-152.
Abstract:
Magnetic homogeneity and flux distribution in Nd Fe B magnets have been studied using a statistic method. The results show that the distribution of magnetic flux is affected by various random factors such as composition, orientational field, and magnetic flux density. The statistic results conform well to a normal Gaussian distribution. Moreover, the main factor affecting magnetic homogeneity is the orientation degree of the easy axis of the powders.
Magnetic homogeneity and flux distribution in Nd Fe B magnets have been studied using a statistic method. The results show that the distribution of magnetic flux is affected by various random factors such as composition, orientational field, and magnetic flux density. The statistic results conform well to a normal Gaussian distribution. Moreover, the main factor affecting magnetic homogeneity is the orientation degree of the easy axis of the powders.
2000(3):153-157.
Abstract:
利用钛与Ｂ４Ｃ，石墨之间的自划算高温合成反应经普通的熔铸工艺原位合成制备了等摩尔ＴｉＣ和增强的钛基复合材料，光学金相、ＥＰＭＡ、ＴＥ几Ｘ射线衍射的研究结果表明：存在两 不同形状的境强体，即短纤维状ＴｉＢ晶须和等轴、近似等轴状ＴｉＣ粒子。境强体与Ｔｉ基体界面洁净，没有明显的界面反应。由于境强体随载荷，基体合金晶粒细化以及高密度位错的存在，制备钛基复合材料的机械性能有了较大的提高。石墨的加入导致形成更
利用钛与Ｂ４Ｃ，石墨之间的自划算高温合成反应经普通的熔铸工艺原位合成制备了等摩尔ＴｉＣ和增强的钛基复合材料，光学金相、ＥＰＭＡ、ＴＥ几Ｘ射线衍射的研究结果表明：存在两 不同形状的境强体，即短纤维状ＴｉＢ晶须和等轴、近似等轴状ＴｉＣ粒子。境强体与Ｔｉ基体界面洁净，没有明显的界面反应。由于境强体随载荷，基体合金晶粒细化以及高密度位错的存在，制备钛基复合材料的机械性能有了较大的提高。石墨的加入导致形成更
2000(3):161-163.
Abstract:
A model for the temperature distribution across the interface during explosive cladding has been proposed. The model can be used to predict and analyse the microstructure of the explosively banded interface, and yields results that agree with those obtained using TEM.
A model for the temperature distribution across the interface during explosive cladding has been proposed. The model can be used to predict and analyse the microstructure of the explosively banded interface, and yields results that agree with those obtained using TEM.
2000(3):164-167.
Abstract:
研究了锻造Ｔｉ－４８Ａｌ－２Ｃｒ（ａｔ％）在１１８０℃热自理音的组织演变，分析在不同温度等温热处理进晶粒长魇 动力学，在Ｔａ以上等温热处理时，昌粒长大迅速，其晶粒长大因子为２．４。在Ｔａ以下等温热处理进，当热处理由１０ｍｉｎ不断延长到４ｈ时，ｒ晶粒尺寸变化较小，α晶粒不断长大。热处理温度越高，晶粒长大越快在１１８０℃，１２２０℃，１２６０℃和１３００℃热处理进晶粒长大因子分别为２．９，２．８．２．
研究了锻造Ｔｉ－４８Ａｌ－２Ｃｒ（ａｔ％）在１１８０℃热自理音的组织演变，分析在不同温度等温热处理进晶粒长魇 动力学，在Ｔａ以上等温热处理时，昌粒长大迅速，其晶粒长大因子为２．４。在Ｔａ以下等温热处理进，当热处理由１０ｍｉｎ不断延长到４ｈ时，ｒ晶粒尺寸变化较小，α晶粒不断长大。热处理温度越高，晶粒长大越快在１１８０℃，１２２０℃，１２６０℃和１３００℃热处理进晶粒长大因子分别为２．９，２．８．２．
2000(3):168-171.
Abstract:
The effects of alkali treatment on the deposition of apatite on various titanium alloy substrates have been studied. The results show that a porous titanium dioxide hydrogel layer with negative charge forms on the substrate during alkali treatment, and the gel layer can induce apatite formation in the simulated body fluid(SBF). The pore diameter, gel thickness and the induction ability of the gel layer increase with the concentration, temperature and treating time of the alkaline solution. The induction abilities of the various substrate materials decreases according to Ti>TC4, Ti75>TiZr. It is concluded the titanium alloys treated by alkali can induce apatite formation in SBF, and are bioactive.
The effects of alkali treatment on the deposition of apatite on various titanium alloy substrates have been studied. The results show that a porous titanium dioxide hydrogel layer with negative charge forms on the substrate during alkali treatment, and the gel layer can induce apatite formation in the simulated body fluid(SBF). The pore diameter, gel thickness and the induction ability of the gel layer increase with the concentration, temperature and treating time of the alkaline solution. The induction abilities of the various substrate materials decreases according to Ti>TC4, Ti75>TiZr. It is concluded the titanium alloys treated by alkali can induce apatite formation in SBF, and are bioactive.
2000(3):177-181.
Abstract:
配制了３种不同成分的Ａｌ－Ｃｕ－Ｍｇ－Ｆｅ－Ｎｉ－（Ｓｃ，Ｚｒ）实验合金，测量了合金在２００℃的时效曲线及室温，３００℃下的拉伸性能，采用金相显微镜、扫描电镜（能谱）和透射电镜观察了合金不同状态下的显微组织。结果表明：加入微量Ｓｃ和Ｚｒ后生成的一次Ａ１３（Ｓｃ，Ｚｒ）相可明显细化基体晶粒，二次析出的Ａ１３（Ｓ质点有明显的时效硬化效果，并且有利于合金中另一强化相Ｓ（Ａ１２ＣｕＭｇ）更均匀析出，从而提
配制了３种不同成分的Ａｌ－Ｃｕ－Ｍｇ－Ｆｅ－Ｎｉ－（Ｓｃ，Ｚｒ）实验合金，测量了合金在２００℃的时效曲线及室温，３００℃下的拉伸性能，采用金相显微镜、扫描电镜（能谱）和透射电镜观察了合金不同状态下的显微组织。结果表明：加入微量Ｓｃ和Ｚｒ后生成的一次Ａ１３（Ｓｃ，Ｚｒ）相可明显细化基体晶粒，二次析出的Ａ１３（Ｓ质点有明显的时效硬化效果，并且有利于合金中另一强化相Ｓ（Ａ１２ＣｕＭｇ）更均匀析出，从而提
2000(3):182-184.
Abstract:
Some ternary Ni Ti Nb based shape memory alloys have been prepared in the water cooled crucible of a magnetic suspension furnace under a controlled protective argon atmosphere. Anodic polarization curves of the Ni Ti Nb based shape memory alloys were measured utilizing the Montaklo Mode. The stability of the passive film was investigated in both artificial sea water (3 5%NaCl) and physiological solution (5%NaCl+0.1%H 2O 2) environments. The results show that the corrosion resistance of these alloys is excellent.
Some ternary Ni Ti Nb based shape memory alloys have been prepared in the water cooled crucible of a magnetic suspension furnace under a controlled protective argon atmosphere. Anodic polarization curves of the Ni Ti Nb based shape memory alloys were measured utilizing the Montaklo Mode. The stability of the passive film was investigated in both artificial sea water (3 5%NaCl) and physiological solution (5%NaCl+0.1%H 2O 2) environments. The results show that the corrosion resistance of these alloys is excellent.
2000(3):185-189.
Abstract:
The effects of strain rate and temperature on the tensile yield strength and elongation of titanium aluminides are studied. The alloy Ti 45Al 10Nb(at%) has a fully lamellar microstructure. The test results show that the brittle ductile transition(BDT) temperature increases with the increases of strain rate and temperature. The activation energy is 330kJ/mol, which approximates to the self diffusion activation energy of atoms in the TiAl alloy. Fractography and dislocation configuration analyses demonstrate that the brittle ductile transition of the alloy Ti 45Al 10Nb is controlled by dislocation climb.
The effects of strain rate and temperature on the tensile yield strength and elongation of titanium aluminides are studied. The alloy Ti 45Al 10Nb(at%) has a fully lamellar microstructure. The test results show that the brittle ductile transition(BDT) temperature increases with the increases of strain rate and temperature. The activation energy is 330kJ/mol, which approximates to the self diffusion activation energy of atoms in the TiAl alloy. Fractography and dislocation configuration analyses demonstrate that the brittle ductile transition of the alloy Ti 45Al 10Nb is controlled by dislocation climb.
2000(3):193-196.
Abstract:
MgNi x(x=0 5,1 0,1 25,1 5,2 0)binary alloys have been synthesized using mechanical alloying(MA). The effect of nickel on the structure and electrochemical properties of MA Mg Ni binary alloys has been investigated. All MA MgNi x(x=1 0,1 25,1 5,2 0) alloys, except MgNi 0 5 are amorphous. The properties of the amorphous alloys are better than those of the crystallite one. As the nickel content in amorphous alloys increases, the maximum discharge capacity decreases and the average potential moves towards negative direction, but the decay of charge discharge capacity decreases.
MgNi x(x=0 5,1 0,1 25,1 5,2 0)binary alloys have been synthesized using mechanical alloying(MA). The effect of nickel on the structure and electrochemical properties of MA Mg Ni binary alloys has been investigated. All MA MgNi x(x=1 0,1 25,1 5,2 0) alloys, except MgNi 0 5 are amorphous. The properties of the amorphous alloys are better than those of the crystallite one. As the nickel content in amorphous alloys increases, the maximum discharge capacity decreases and the average potential moves towards negative direction, but the decay of charge discharge capacity decreases.
2000(3):200-203.
Abstract:
The corrosion rates of uranium in dry HCl air and air medium have been studied. The results show that the corrosion products are almost the same in dry HCl air as in dry air, but corrosion rates tend to be different. The main surface oxides formed are UO 2 and UO 2+x . The presence of HCl can accelerate the corrosion. Uranium reacts with hydrogen in HCl, producing uranium hydride which in return reacts with oxygen and chlorine to produce hydrogen. This reaction significantly decreases the lifetime of the uranium.
The corrosion rates of uranium in dry HCl air and air medium have been studied. The results show that the corrosion products are almost the same in dry HCl air as in dry air, but corrosion rates tend to be different. The main surface oxides formed are UO 2 and UO 2+x . The presence of HCl can accelerate the corrosion. Uranium reacts with hydrogen in HCl, producing uranium hydride which in return reacts with oxygen and chlorine to produce hydrogen. This reaction significantly decreases the lifetime of the uranium.
2000(3):204-206.
Abstract:
采用自然时效、人工时效等热处理工艺，借助航向电镜和室温低频扭摆内耗仪，研究了微量Ｃｅ，Ｌａ对高阻尼Ｚｎ－２２％Ａｌ合金时效后显微组织和阻尼性能（内耗）的影响。结果表明，经水淬后８０℃温轧的Ｚｎ－２２％Ａｌ合金在低于温轧温度下时效时，其阻尼性能 量Ｃｅ，Ｌａ的加入，提高了经水淬后８０℃温轧的Ｚｎ－２２％Ａｌ合金的阻尼性能，减缓了经１５０℃时效后阻尼性能的降低。
采用自然时效、人工时效等热处理工艺，借助航向电镜和室温低频扭摆内耗仪，研究了微量Ｃｅ，Ｌａ对高阻尼Ｚｎ－２２％Ａｌ合金时效后显微组织和阻尼性能（内耗）的影响。结果表明，经水淬后８０℃温轧的Ｚｎ－２２％Ａｌ合金在低于温轧温度下时效时，其阻尼性能 量Ｃｅ，Ｌａ的加入，提高了经水淬后８０℃温轧的Ｚｎ－２２％Ａｌ合金的阻尼性能，减缓了经１５０℃时效后阻尼性能的降低。
2000(3):207-210.
Abstract:
依据锆（ＩＶ）对Ｈ２Ｏ２氧化Ｂｅｉ花青褪色的催化行为，建立了测定痕量锆的催化动力学分析法。本法线性范围为０～１１０ｎｇ／ｍｌ，检测限为０．４ｎｇ／ｍｌ。除Ｃｒ（ＶＩ），Ｃｕ＾２＋和Ｆｅ＾３＋外，其余离子不影响测定。其干扰可用ＥＤＴＡ和甘露醇掩蔽消除，也可将Ｃｒ（ＶＩ）还原为Ｃｒ（Ⅲ）而消除其影响；测定了锆青铜及合成样品中的锆，结果满意。
依据锆（ＩＶ）对Ｈ２Ｏ２氧化Ｂｅｉ花青褪色的催化行为，建立了测定痕量锆的催化动力学分析法。本法线性范围为０～１１０ｎｇ／ｍｌ，检测限为０．４ｎｇ／ｍｌ。除Ｃｒ（ＶＩ），Ｃｕ＾２＋和Ｆｅ＾３＋外，其余离子不影响测定。其干扰可用ＥＤＴＡ和甘露醇掩蔽消除，也可将Ｃｒ（ＶＩ）还原为Ｃｒ（Ⅲ）而消除其影响；测定了锆青铜及合成样品中的锆，结果满意。
2000(3):211-215.
Abstract:
The processing of continuous fiber reinforced titanium alloy matrix composites (Ti MMCs) is reviewed in this paper. Special attention is placed on three processing methods: fiber foil fiber(FFF), plasma coating (PCM) and physical vapor deposition (PVD). The research progress in reinforcing fiber and matrix alloy selection is discussed. Particular attention being paid to the fibers SiC and Al 2O 3. The mechanical properties and damage evaluation of the composites are also presented.
The processing of continuous fiber reinforced titanium alloy matrix composites (Ti MMCs) is reviewed in this paper. Special attention is placed on three processing methods: fiber foil fiber(FFF), plasma coating (PCM) and physical vapor deposition (PVD). The research progress in reinforcing fiber and matrix alloy selection is discussed. Particular attention being paid to the fibers SiC and Al 2O 3. The mechanical properties and damage evaluation of the composites are also presented.
