X.T.Liu
,
J.Z.Cui
金属学报(英文版)
With an electric field during austenitizing, the martensite transformation of the low carbon steel was promoted, and more martensite were obtained. The electric field promotes the homogeneity of carbon, and reduces the free energy of austenite. The critical neuclus r^* and the critical driving force G^* responsible for the nucleation of proeutectoid ferrite were increased. As a result of which the diffusion controlled proeuctoid ferrite transformation was retarded and the hardenability was improved.
关键词:
austenization
,
null
,
null
X.T.Liu
,
J.Z.Cui
金属学报(英文版)
Microstructure evolution of wrought aluminum alloy extruded rods and the mechanism of liquid phase formation during reheating were investigated. And the relation between the volume fraction of liquid phase and the recrystallization microstructure was proposed. The results show that increase in reheating temperature and time can augment the volume fraction of liquid phase and accelerate the grain spheroidization, as a result of which the requirement of semi-solid forming can be satisfied. Due to the higher aberration energy of grain boundary, the melting point is lowered as a result of the easy diffusion of atoms. At higher reheating temperature the grain boundary melts, the growth of the recrystallized grain is inhibited and the grain is refined. The composition of the low melt-point phase along the recrystallized grains was determined using EDS. It can be seen from the experimental results that when the extrusion rod of the wrought aluminum alloy is reheated at 610℃ for 20min, perfect fine equiaxial grains can be obtained, the average grain size is about 66.34μm and the volume fraction of solid phase is about 68%.
关键词:
wrought aluminum alloy
,
null
,
null
FAN Zhanguo
,
JI Chunlin
,
WANG Kuihan
,
CUI Chuanmeng
,
LIU Sulan
,
Northeast University of Technology
,
Shenyang
,
China
金属学报(英文版)
A unidirectional reaction for synthesis of the high T_c superconductor YBa_2Cu_3O_x has been proposed, Its T_c is 90-94.5 K and △T is 1 K. The phase relationships in the system Y_2BaCuO_5-Y_2Cu_2O_5-CuO-YBa_2Cu_3O_x were studied and discussed.
关键词:
unidirectional reaction
,
null
,
null
韩志达
,
崔荣静
,
江学范
,
王敦辉
,
都有为
稀有金属
doi:10.3969/j.issn.0258-7076.2010.01.022
通过示差扫描量热仪和振动样品磁强计对Ni_(43)Mn_(46-x)T_xSn_(11)(T=Fe,Co,Ni)铁磁形状记忆合金的相变、磁性以及磁熵变进行了研究.结果表明,由于价电子浓度的增加,Fe,Co,Ni替代Mn使马氏体转变温度大幅提高.Fe,Ni掺杂对马氏体居里温度(Tc_M)影响不大,Co则使T_c~M略有下降;奥氏体居里温度(T_c~A)对成分比较敏感,Fe,Ni的加入均使T_c~A略有提高,而Co则会大大提高T_c~A.由于马氏体相变伴随着磁化强度的突变,Ni_(43)Mn_(46-x)T_xSn_(11)合金在马氏体相变附近具有较大的低场磁熵变,对于Ni_(43)Mn_(41)Co_5Sn_(11)在室温1 T磁场下磁熵变达到了19 J·kg~(-1)·K~(-1).通过调节成分,磁熵变峰值温度可以在199和294 K之间调节,同时保持了较大低场磁熵变.
关键词:
铁磁形状记忆合金
,
磁熵变
,
磁制冷
张金玲
,
祁小叶
,
王社斌
,
许并社
材料热处理学报
在不同的T4和T6热处理参数下,对AZ91+x％La镁合金在的组织和硬度的变化进行了研究.结果表明,T4(410℃+16 h)固溶处理后,由于合金的大部分β相都溶入基体中,硬度比铸态时有所下降；T6( 170℃+24 h)时效处理后,基体上析出了大量晶界分布或在α相晶粒内的层片状β-Mg17Al12相,合金硬度得到显著提高,且AZ91 +0.16％ La镁合金时效态试样的硬度最高,可达138 HV.
关键词:
AZ91镁合金
,
稀土La
,
T4热处理
,
T6热处理
Journal of Alloys and Compounds
As hydrogen, deuterium and tritium storage materials, a series of investigations of mechanical and thermal properties of titanium hydrides, deuterides and tritides have been performed, however, very limited theoretical studies of thermodynamic properties for them can be found. Based on density-functional theory (DFT) and density-functional perturbation theory (DFPT) we have discussed systematically the hydrogen isotope effects on the thermodynamic properties of TiX2 (X = H, D, and T) system. Our calculations indicate that for evaluating accurately their physical properties at absolute zero temperature, such as the equilibrium lattice constants, bulk modulus, and heat of formation, the zero-point energy correction must be taken into account. By performing the phonon calculation within quasiharmonic approximation (QHA), we obtain their vibrational free energies, vibrational entropies, and temperature dependence of specific heat, thermal expansion, and bulk modulus. Those results demonstrate that comparing with TiH2, TiT2 and TiD2 are more stable and the zero-point effects play an important role in their thermal expansion. The increase in the force constant between Ti and H causes the higher value of specific heat of TiH2 during the phase transition from FCC to FCT. In addition, comparing with available experimental values, we can conclude that QHA is feasible for describing the thermal properties of TiX2. (C) 2006 Elsevier B.V. All rights reserved.
关键词:
isotope effects;thermodynamic properties;density-functional;perturbation theory;quasiharmonic approximation;functional perturbation-theory;neutron spectroscopy;thermal-properties;titanium;hydrogen;dependence;expansion;constants;palladium;hydrides
罗磊
,
赵长亮
,
陈玉鑫
,
袁天祥
钢铁
doi:10.13228/j.boyuan.issn0449-749x.20130716
通过对首钢京唐公司生产的X80管线钢复吹转炉炼钢过程磷质量分数的控制研究,从热力学上分析了炼钢终点渣钢间磷分配比较低的原因,同时给出了转炉终渣成分的调节方向,以及要得到相应脱磷率和终点磷分配比时转炉渣加入量的最佳值.研究结果表明,在现有工艺条件下,转炉炉渣中MgO质量分数偏高,导致终渣熔点较高,而转炉终点渣熔点较高又是转炉磷分配比实际值与理论值差距较大的主要原因.通过计算,在现有工艺水平下,转炉渣的加入量应控制在43～60 kg/t(钢)较为合适.
关键词:
X80管线钢
,
复吹转炉
,
磷容量
,
转炉炉渣
白世武
,
童莉葛
,
隋永莉
,
王立
,
康奇兰
金属世界
doi:10.3969/j.issn.1000-6826.2009.z1.013
焊接热输入和冷却时间是影响焊接温度场分布的重要参数.本文利用有限元软件ANSYS对X80管线钢复合坡口多道焊的焊接过程进行二维模拟,研究每道填充焊层T8/5的变化规律.结果表明,热输入对T8/5的影响最大;T8/5随热输入的增加而增大;由于前一道焊对后一道焊的预热作用,T8/5随焊道数的增多而增大;当层间温度等于预热温度时,各层的T8/5趋于一致.合理选择预热温度和层间温度可以有效控制各焊道的T8/5.
关键词:
管线钢
,
多道焊
,
有限元
,
温度场
丰崇友
,
刘向东
,
李洪波
兵器材料科学与工程
doi:10.3969/j.issn.1004-244X.2007.03.011
对08X18H10T不锈钢进行单轴及多轴非比例循环加载低周疲劳试验及其微结构的观察,分析单轴及多轴非比例加载低周疲劳特性及其变形微观机理,结果表明:多轴非比例加载过程中,奥氏体不锈钢08X18H10T产生明显的非比例附加强化;在应变幅值较大时,塑性变形不仅通过滑移方式进行,还有孪生变形方式,微观形貌由平面状滑移向波纹状滑移转化.
关键词:
08X18H10T不锈钢
,
非比例循环载荷
,
附加强化
,
位错
,
孪晶
