P. R. Ding
,
D. Y. Ju
,
T. Lnouc and E. de Vries( 1) MSC Japan Ltd.
,
Osaka
,
Japan 2) Saitama Institute of Technology
,
Saitama
,
Japan 3) Kyoto Universily
,
Kyoto
,
Japan 4) MacNeal - Schwendler (E. D. C. ) B. V.
,
Gouda
,
The Netherlands)
金属学报(英文版)
A method to simulate processes of forging and subsequent heat treatment of an axial symmetric rod is formulated in eulerian description and the feasibility is investigated. This method uses finite volume mushes for troching material deformation and an automatically refined facet surface to accurately trace the free surface of the deforming material.In the method,the deforming work piece flows through fixed finite volume meshes using eulerian formulation to describe the conservation laws,Fixed finite volume meshing is particularly suitable for large three-dimensional deformation such as forging because remeshing techniques are not required, which are commonly considered to be the main bottelencek in the ssimulations of large defromation by using the finite element method,By means of this finite volume method, an approach has been developed in the framework of "metallo-thermo-mechanics" to simulate metallic structure, temperature and stress/strain coupled in the heat treatment process.In a first step of simulation, the heat treatment solver is limited in small deformation hypothesis,and un- coupled with forging. The material is considered as elastic-plastic and takes into account of strain, strain rate and temperature effects on the yield stress.Heat generation due to deformation,heat con- duction and thermal stress are considered.Temperature - dependent phase transformation,stress-in- duced phase transformation,latent heat,transformation stress and strain are included.These ap- proaches are implemented into the commerical commercial computer program MSC/SuperForge and a verification example with experimental date is given as comparison.
关键词:
finite volume method
,
null
,
null
,
null
,
null
陈婷
,
卢婷利
,
马玉樊
,
王韵晴
,
校月红
,
李昱辉
材料导报
在多肽EAK16水凝胶支架上接种小鼠前成骨细胞MC3T3-E1,采用倒置显微镜观察细胞形态,CCK-8(细胞计数试剂盒)检测细胞增殖情况.细胞在诱导培养基中培养1周后,观察不同时间段细胞碱性磷酸酶的分泌活性.采用ALP染色和茜素红-S染色作为定性实验研究MC3T3-E1向成骨方向的分化情况.结果表明,MC3T3-E1细胞在水凝胶支架EAK16上有较好的黏附和增殖能力,诱导培养后细胞有较高水平的碱性磷酸酶表达和矿化基质沉积.多肽水凝胶支架对前成骨细胞MC3T3-E1具有较好的生物相容性.
关键词:
自组装多肽水凝胶
,
MC3T3-E1细胞
,
成骨分化
,
组织工程
Physical Review B
Magnetoresistance has been studied for quasi-two-dimensional thallium purple bronze T1Mo6017 at a temperature of 4.2 K in fields up to 12 T. Shubnikov-de Haas oscillations are observed. The calculated Fermi surface size is about 5x10(-4) in the high-temperature Brillouin zone and consistent with hidden Fermi surface nesting theory. The field dependence of magnetoresistance is studied in the vicinity of magnetic breakdown. The characteristic field of breakdown is around 0.08 T corresponding to an energy gap of about 2 meV. The effective mobility and cyclotron mass are about 0.025 m(2) V-1 s(-1) and 0.3m(e), respectively.
关键词:
molybdenum bronzes;instability
ZHANG Xi-liang
,
ZHOU Chang-yu
钢铁研究学报(英文版)
The constant embrittlement curve for constant segregation concentration on grain boundary of impurity element P and relationship between equilibrium grain boundary segregation concentration and operation time for 225Cr-1Mo steel were derived based on the theory of equilibrium grain boundary segregation. The mechanism of step-cooling test and mechanism of de-embrittlement for 225Cr-1Mo steel were explained. The segregation rate will increase but equilibrium grain boundary segregation concentration of impurity element P will decrease as temperature increases in the range of temper embrittlement temperature. There is one critical temperature of embrittlement corresponding to each embrittlement degree. When the further heat treating temperature is higher than critical temperature, the heat treating will become a de-embrittlement process; otherwise, it will be an embrittlement process. The critical temperature of embrittlement will shift to the direction of low temperature as further embrittlement. As a result, some stages of step-cooling test would change into a de-embrittlement process. The grain boundary desegregation function of impurity element P was deduced based on the theory of element diffusion, and the theoretical calculation and experimental results show that the further embrittlement or de-embrittlement mechanism can be interpreted qualitatively and quantitatively by combining the theory of equilibrium grain boundary segregation with constant embrittlement curve.
关键词:
step-cooling test
,
critical embrittlement temperature
,
embrittlement mechanism
,
grain boundary desegregation
牟淑坤
,
栗卓新
,
张飞虎
,
陈延清
,
章军
,
刘宏
机械工程材料
采用不同的热输入(12.98,15.88,18.47,20.37,22.59 kJ·cm-1)、用E81T1-K2药芯焊丝对FH36船用钢板进行焊接,研究了热输入对熔敷金属显微组织和-60℃低温冲击韧性的影响.结果表明:熔敷金属的-60℃低温冲击韧性随着热输入的增加而呈现先升高后降低的变化趋势,当热输入为18.47kJ·cm-1时达到最大值79 J;随热输入的增加,晶界铁素体和侧板条铁素体的面积分数均先减小后增加,针状铁素体的面积分数先增加后减小,并在热输入为18.47kJ·cm-1时达到最大,为85.2％.
关键词:
热输入
,
药芯焊丝
,
冲击韧性
李贤
,
汪炬
,
周长忍
,
田金环
,
陈小佳
,
赵名艳
材料科学与工程学报
以脐血来源的间充质干细胞(UCB-MSC)为研究对象,应用MTT方法观测壳寡糖对细胞增殖的影响,荧光定量PCR技术研究壳寡糖对细胞周期蛋白cyclinD1和骨特异转录因子RUNX2mRNA表达的调控.结果显示壳寡糖还可促进脐血间充质干细胞增殖,且浓度为300μg/ml的壳寡糖作用最为显著.同时荧光定量PCR结果说明壳寡糖上调cyclin D1和RUNX2基因表达,即一方面壳寡糖通过提高cyclin D1的水平促进脐血间充质干细胞的增殖,另一方面其可通过上调RUNX2的表达促进细胞向成骨细胞分化.
关键词:
壳寡糖
,
脐血间充质干细胞
,
细胞周期蛋白D1
,
RUNX2
K. Mii (Sumitomo Metal Industries
,
Ltd.
,
1-t-3 Otemachi
,
Tokyo 100
,
Japan)M Amano (National Research Institute for Metals
,
1-2-1 Sengen
,
Tsukuba 305
,
Japan)
金属学报(英文版)
The R & D of hydrogen absorbing alloys in Japan started in the early 1970s.Many alloys such as TiMm1.5 based alloys, Fe-Ti-O alloys (e.g. FeTi1.15 O0.024) andthe(mischmetal)Ni5 based alloys (e.g. MmNi4.5 Cr0.46 Mn0.04) were developed by the early 1980s. The application of these alloys to hydrogen storage, heat storage, heat pump, hydrogen purification and motor vehicles has been tried in many iaboratories,and the various techniques for using hydrogen absorbing alloys have been developed.The standarkization of evaluation methods for hydrogen absorbing alloys has been promoted by the Ministry of International Trade and Industry (MITI), and four of them were established as Japanese Industrial Standard (JIS).Alloys for Ni-Metal Hydride batteries have been extensively investigated since 1987in Japun. Mm-Ni-Co-Al-Mn alloys (e.g. MmNi3.55 Co0.75Al0.9Mn0.4) have been devel-oped and commereialized since 1990. The amount of production of small-size Ni-MH batteries in 1995 was about three hundred milliion in number and about one hundred billion yen. The R & D for higher enerpy-density Ni-MH batteries is intensively in progress.MITI and STA (Science and Technology Agency) have promoted the R & D of hydro-gen absorbing alloys in Japan by carrying out the national projects such as Sunshine Program (MITI: 1974-1993) and Utilization of Wind Engeray (STA 1980-1985). The New Sunshine Program (MITI 1993-2020) have started in 1993. This program con-tains the application of hydrogen absorbing alloys to Economical- Enerpy- City System and to We-NET (International Clean Energy System of Technology Utilizing Hydro-gen: World Energy Network.
关键词:
hydrogen absorbing alloy
,
null
,
null
,
null
赵常就
,
陈林生
,
赵子微
中国腐蚀与防护学报
本工作采用恒电量技术,分析恒电量微扰下的△E～t衰减曲线以获得塔菲尔斜率。这种断电的松弛方法不受溶液电阻的影响,因而特别适用于高阻介质和涂装金属体系。该方法以电化学基本方程为基础,结合恒电量微扰技术原理。使用基尔霍夫和结点电流公式列出微分方程组,然后采用四阶龙格——库塔法解微分方程组。可将△E值缩小到±10mV的范围。对几个实验体系所进行的试验验证了本方法的可行性。
关键词:
Chinese Physics Letters
The magnetic properties of 1 T-TaS2 and 1 T-Fe-0.07 Ta-0.93 S-2 have been studied, Experimental results show that the phase transition temperature of 1 T-TaS2 is a function of the magnetic field, At low temperatures, both compounds are in a mixed state of charge density wave -spin density wave due to the coherent superposition of antiferromagnetic coupling.
关键词:
density
