曹富荣管仁国丁桦李英龙周舸崔建忠
金属学报
doi:10.3724/SP.J.1037.2009.00582
采用熔铸和大变形轧制制备了Mg-6Li-3Zn合金板材, 研究了合金的高温变形行为、显微组织、空洞与位错蠕变机制. 在623 K和1.67×10-3 s-1条件下获得了300%的最大延伸率. OM, TEM和SEM观察显示, 合金带状晶粒组织在573 K和1.67×10-3 s-1条件下发生显著的动态再结晶, 亚晶轮廓不清晰,位错分布比较均匀. 合金在573-623 K和1.67×10-3 s-1条件下断裂形式为韧性断裂. 获得了新型的位错黏性滑移与位错攀移转变蠕变机制图,表明Mg-6Li-3Zn合金带状晶粒组织在573 K和1.67×10-3 s-1条件下高温变形机制为晶格扩散控制的位错黏性滑移, 其应力指数为3(应变速率敏感性指数0.33), 变形激活能为134.8 kJ/mol, 与Mg的晶格扩散激活能相同.获得了新型的考虑聚合的空洞长大图, 合金在573 K和1.67×10-3 s-1条件下的空洞长大机制为塑性控制的空洞长大.
关键词:
Mg-Li-Zn合金
,
dislocation creep
,
quasi-superplasticity
,
mechanical property
,
cavity
赵友昌
,
刘爱红
金属学报
本文研究了Al-Zn-Mg-Zr-RE(A合金)及Al-Zn-Mg-Ti(B合金)的超塑性,并用X射线小角散射方法较系统的研究了不同应变速率不同变形度的亚稳定微空洞体积分数的变化规律,同时用定量金相方法测定了稳定空洞的长大规律,实验证明:A合金亚稳定空洞体积分数比B合金高,微空洞形核速率比B合金大,但A合金的稳定空洞长大速率比B合金小,故A合金的超塑性优于B合金。
关键词:
Al-Zn-Mg合金
,
superplasticity
,
cavity
,
strain rate
王富岗
,
祝苏明
,
朱世杰
,
任晓民
,
谭毅
,
张俊善
金属学报
在两种不同晶界状态下研究了Fe-Cr15-Ni25合金的蠕变裂纹扩展行为。单相合金的空洞在晶界三叉点处形核,而对晶界上有碳化物析出的合金,空洞在晶界碳化物上形核。晶界碳化物阻碍了空洞的长大和连接,因而大大提高了蠕变裂纹扩展抗力。
关键词:
蠕变
,
crack growth
,
grain boundary carbide
,
cavity
,
Fe-Cr15-Ni25 alloy
卢庆港
,
黄胜茂
,
杜亚平
,
代金良
绝缘材料
为了评估长时间充氮无油存放的变压器质量，重点从氮气中水分对绝缘性能的影响、绝缘材料老化降解、空腔及气泡形成等方面进行分析，指出了变压器长期充氮存放可能出现的风险，同时对实际长期存放的变压器的电气性能进行了对比分析。结果表明：采取有效的保护措施后无油充氮存放对产品质量不会造成明显的影响，采取正确的处理工艺后产品质量可以得到较好的恢复，为后续变压器的存放管理提供参考。
关键词:
油浸变压器
,
充氮
,
绝缘
,
水分
,
降解
,
空腔
,
气泡
,
质量
JIANG Xinggang CUI Jianzhong MA Longxiang Northeast University of Technology
,
Shenyang
,
China
金属学报(英文版)
The fractal dimension changes of cavities have been determined during superplastic deformation of the high strength aluminiurn alloy 7475 with different strain,temperature, strain rate and grain size.The fractal dimension of cavities may increase with the increase of strain.It becomes higher as the alloy deformed under lower temperatures,greater strain rate and coarser grain size.The alloy would be approaching to rupture if the fractal dimension of cavities raised to a certain extent.
关键词:
fractal dimension
,
null
,
null
,
null
ZHAO Youchang LIU Aihong Jilin University
,
Changchun
,
China
金属学报(英文版)
The superplasticity of the Al-Zn-Mg-Zr-RE(alloy A)and Al-Zn-Mg-Ti(alloy B),their change of volume fraction of metastable micro-cavities under various reduction of area and strain rates,as well as the growth of stable cavities in them have been studied by means of small angle X-ray scattering analyses and quantitative metalloraphy respectively.Experimen- tal results show that the volume fraction of metastable micro-cavities of the alloy A is more than that of the alloy B,but the growth rate of stable cavities in alloy A is less than that in al- loy B.Thus,it is believed that the superplasticity of alloy A is superior to that of alloy B.
关键词:
Al-Zn-Mg alloy
,
null
,
null
,
null
Y.D. Yu
,
K.F. Zhang
,
H.R. Zheng
,
D.M. Jiang
金属学报(英文版)
Numerical simulation and experimental studies on cavity growth were carried out during the bulging process of superplastic magnesium Alloy. A three-dimensional rigid-
viscoplastic finite element program has been developed and applied to predict the cavity radiusand volume fraction of cavity growth. The final prediction on the cavity
radius and volume fraction distribution was exhibited as colorful shade pictures. The
experimental studies wereperformed under similar conditions to the numerical one
and provided for quantitativecomparison. According to the metallography observation,
the radius and volume fraction of cavity growth was quantitative achieved by using
Profound-Iron & steel software. The numerical results were in reasonable quantitative agreement with the experiment.
关键词:
magnesium alloy
,
null
,
null
,
null
马兵善
,
王刚
,
郭玉龙
工程热物理学报
本文对上下壁面绝热、左侧壁面长度为b的嵌装加热器部分维持恒定温度Th而剩余部分绝热,且右侧壁面维持恒定温度Tc的多孔介质方腔内的自然对流换热进行了数值研究.在热壁面无量纲长度B=0.5 (B=b/L)的条件下,综合研究了左侧壁面受热部分中心距上壁面的无量纲长度D (D=d/L)、Da数、Ra数和孔隙率对腔体内自然对流换热的影响.数值计算结果表明,左侧壁面受热部分位置的不同对腔体内自然对流换热有很大的影响,D在0.6附近取值时,Nu数最大.Da数、Ra数对腔体的自然对流换热影响较大,而孔隙率对换热的影响较小.
关键词:
自然对流
,
多孔介质
,
方腔
,
数值模拟
