HUANG Xue-wen, DONG Guang-neng, WANG Hui, ZHOU Zhong-rong, XIE You-bai. Study on Damping Characteristics of TiNi Shape Memory Alloy[J]. Journal of Materials Engineering, 2003, 0(5): 3-6,14.
The low-frequency dynamic damping capacity for Ti-50.8Ni(atom fraction,%)shape memory alloy was investigated by means of DMTA(dynamic mechanical thermal analysis)method with the frequency and temperature varied.The results indicate that the annealed Ti-50.8Ni alloy exhibits better damping capacity than aged alloy and the damping capacity of martensite phase and R phase are higher than that of parent phase,during the phase transformation the damping capacity originated from phase transformation firstly increases up to a maximum and then drops with the temperature,meanwhile,the tendency of elastic modulus is contrary to that of damping.The effect of frequency on damping capacity due to phase transformation was also studied and it is demonstrated that damping capacity varies inversely with frequency but elastic modulus is not affected by frequency.The damping capacity is not sensitive to temperature or frequency after phase transformation finished.Multi-phase-transformation for annealed Ti-50.8Ni alloy occurs owing to the combination of temperature and stress during cooling process,which results in multi-maximum of damping capacity.
YU Hui-chen, XIE Shi-shu, LÜJun-ying, ZHAO Guang-pu, YANG Hong-Cai. Microstructures Control in Ni-base Superalloy GH141[J]. Journal of Materials Engineering, 2003, 0(5): 7-10.
The effects of heat treatment on microstructures in Ni-base superalloy GH141 were investigated.The results show that a normal grain growth is closely related with dissolution of γ'phases and carbides during solution treating at 1080~1120℃.γ'phases coarsened by the step growth mechanism change from round shape to cubic one during ageing at 760~900℃,following the lattice diffusion controlled growth rule(Ostwald ripening).The coarsening active energy is 276.8kJ/mol.
LIU Tian-qi, ZHI Min-xue, ZHU Jie-yuan, LI Zhi, LIU Xian-min, ZHAO Zhen-ye. Factors Governing Yield Strength of 30CrMnSiNi2A Steel Melted by VIM+VAR[J]. Journal of Materials Engineering, 2003, 0(5): 11-14.
The factors governing yield strength(σ0.2)of 30CrMnSiNi2A steel melted by VIM+VAR were analyzed.The results show that the C and Si contents have significant effect on the yield strength of this steel.To guarantee the yield strength to meet the requirements of the specification,the elements C and Si must be controlled to the upper limit,and the tempering temperature must be in the higher figures at 200～300℃.
SUN Dong-li, WANG Mei-ling, WANG Xiu-fang, WU Gao-hui. Influence of Aging in Electric Field on Microplastic Deformation Behavior of LY12 Al Alloy[J]. Journal of Materials Engineering, 2003, 0(5): 15-18.
The influence of electric field intensity during aging in an electric field on the microyield strength and micro-plastic deformation behavior of LY12 aluminum alloy was studied.Moreover,the microplastic deformation behaviors of the alloy after aging in a direct current electric field and pulse electric field,were studied respectively.The results show that the microyield strength of the alloy is obviously improved by an appropriate procedure of aging in an electric field and the optimum processing parameter is E=2kV/cm,190℃/10h.
BAO Jian-wen, XU Song-hua, LI Ye, CHEN Xiang-bao. Properties of M40J/EB99-1 Composites Cured by Electron Beam[J]. Journal of Materials Engineering, 2003, 0(5): 19-22.
The normal mechanical properties of M40J/EB99-1 composites cured by electron beam(EB)were investigated,including tensile properties,compression properties,short beam shear strength and flexural properties.The thermal fatigue properties and thermo-physical properties of M40J/EB99 1 composites also were investigated.The results show that,compared with thermal curing M40J/5228 and M40/4211 composites,M40J/EB99-1 composites possess more excellent mechanical properties,and its thermal fatigue resistance is more excellent.
ZHANG Wei, ZHANG Bo-ming, MENG Song-he, HAN Jie-cai. Study of Ablation Behaviors of 3D Fine Weave Pierced Carbon/Carbon Composites Using Plasma Torch at High Temperature[J]. Journal of Materials Engineering, 2003, 0(5): 23-25.
A new method,used plasma torch as the heater,of testing the ablation behaviors of carbon/carbon composites at high temperature was developed,and the ablation resistance of 3D fine weave pierced carbon/carbon composites at high temperature was studied using this method.It is concluded that ablation behaviors of the sample are changed from the center flame region predominantly influenced by thermomechanical attack to the region close to outer flame influenced mainly by thermochemical attack.The thermomechanical ablation resistance of carbon matrix is equal to that of carbon fibers,but the resistance of thermochemical ablation of carbon fibers is significantly enhanced compared to that of carbon matrix.
WANG Wei-guo, H Yasuda, CHU Feng-min, SONG Ming-hui, K Furuya. Microstructures and Valence States of CeO2 Implanted with Hydrogen Ion at Room Temperature[J]. Journal of Materials Engineering, 2003, 0(5): 26-28,18.
The microstructures and valence states of sintered CeO2 implanted with hydrogen ion at room temperature were in-situ observed and analyzed via high resolution transmission electron microscope(HRTEM)and electron energy loss spectrum(EELS).The results indicate though hydrogen ion implantation at room temperature results in a evident change of the chemical state of oxygen in the severely damaged zones,it does not cause CeO2 to transform and cerium to change its valence state.The discussion points out such unexpected results might be attributed to the small size of hydrogen ions,which can not occupy the normal lattice sites of CeO2 and no oxygen vacancies are effectively generated,as well as to the uneasiness of diffusion of Ce and O in CeO2 crystal at room temperature.
ZHANG Lei, YAN Chuan-wei, QU Qing, SUN Gang, TONG Jing-yu, LI Jin-hong, CAO Chu-nan. Study of αs Inorganic Thermal Control Coatings and Their Protection for Space Materials[J]. Journal of Materials Engineering, 2003, 0(5): 29-32,36.
Two low sunlight absorption inorganic thermal control coatings were prepared and the factors(resin type,filler type,ratio of resin to pigment,etc.)which have influence on the properties were also investigated.Surface properties of thermal control coatings were analyzed after exposure to ground-simulated fast atomic oxygen(AO)radiation environment.The surfaces of the coatings with and without exposure to AO were analyzed with scanning electron microscopy(SEM)and spectrophotometer.The results indicate that thermal control coatings have excellent properties for anti-AO effects and good stablility for space environment Specially,10-3 inorganic thermal control coating has the lowest αs value,and is the most stable.
MU Xiao-dong, XIANG Xing-hua, LIU Zheng-yi. Hardness and Microstructure Changing of Fe-base Amorphous Alloy Coating during Crystallizing Process[J]. Journal of Materials Engineering, 2003, 0(5): 33-36.
A kind of Fe-B base amorphous alloy coating(contains Cr,Ni,W,Mo,C,Si)was fabricated by plasma spraying,and the coating was heat-treated at different temperature(100~730℃)for 4h respectively.The DSC test shows that the coating's crystallizing temperature is about 590℃.The heat treatment results show that,when the heat treatment temperature is below 450℃,the coating is still amorphous structure,and the hardness changes a little.When the heat treatment temperature is in the range of 450~610℃,the content of crystallizing phases increases gradually with the temperature improving,the crystallizing phases consist of Fe23(C,B)6,Fe23B6 and rich-Fe phase,and the grain size of crystallizing phase is very small(that is about 20nm after 590℃-4h heat treatment),so the hardness increases rapidly.The hardness of the coating up to maximum value(about 1270HV)after 610℃-4h heat treatment.When the heat treatment temperature is in the range of 630~730℃,rich Fe phase becomes a primary microstructure,and the grain grows up to 5μm after 660℃-4h heat treatment.Although some Fe23(C,B)6,Fe23B6,Fe3B and FeB phase exist in the coating,the hardness decreases rapidly with the temperature increasing.
LIU Fu-rong, GAO Qian, GAO Deng-pan, WANG Guang-sheng. Cracking Analysis of WC Reinforced Composites Coating by Laser Cladding[J]. Journal of Materials Engineering, 2003, 0(5): 37-39.
The cracking behavior of WC reinforced composite coating by laser cladding was investigated.The results show that the effect of cracking is due to the different thermal expansion coefficients between the matrix and the coating.At the same time,the cracking is affected by the laser cladding process parameters,the alloy powders content,the shape and size of the reinfored phases.
WAN Ling, PENG Xiang-he, YANG Yun-min, CHEN Yu-ze, YIN Yi-hui, CHEN Gang. Effect of Temperature and Heating-rate History on Mechanical Properties of H62 and 1Cr18Ni9Ti[J]. Journal of Materials Engineering, 2003, 0(5): 40-42,25.
Using a Gleeble 1500 thermal-mechanical testing system,a systematic experimental investigation to the effect of temperature and heating-rate history on the mechanical properties of brass H62 and stainless steel 1Cr18Ni9Ti was performed.The results show that the mechanical behavior of these materials is influenced by both temperature and heating-rate history.With the increase of temperature,the strength of materials decreases.On the other hand,the micro-structure of materials varies in complex ways with high heating-rate histories,which can be attributed to thermal-inconsistency due to the differences in local physical and mechanical properties.
LU Shi-qiang, HUANG Bai-yun, HE Yue-hui, HE Shuang-zhen, DENG Yi-da. Mechanical Properties of Laves Phase Alloys[J]. Journal of Materials Engineering, 2003, 0(5): 43-47.
Mechanical properties and their present research levels of some Laves phase alloys are introduced,including hardness,strength,ductility,mechanical behavior and fracture toughness.The further research directions for Laves phase alloys are suggested.
