XING Liqian
,
CHEN Xichen
,
Institute of Physics
,
Academia Sinica
,
Beijing
,
ChinaYANG Gencang
,
ZHOU Yaohe
,
Northwestern Polytechnic University
,
Xi'an
,
ChinaGUO Zhenqi
,
Northwestern University
,
Xi'an
,
China XING Liqian
,
Postdoctoral
,
Institute of Physics
,
Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
The glass formability of Ni_(75)B_(17)Si_8 melt and the thermostability of this metallic glass formed from the the melt can be enhanced by eliminating the heterogeneous catalystg. The purification was done by cyclical superheating melt in special glasses and subsequently cyclically superheating it in an electromagnetic levitation apparatus. The purified Ni_(75)B_(17)Si_8 amorphous sample sized up to 20 ~ I0 x 0.5 mm was prepared as four times the thickness of unpurified ones.
关键词:
metallic glass
,
null
,
null
,
null
ZHANG Rong
,
ZHOU Lubin
,
Northwestern Polytechnical University
,
Xi'an
,
ChinaZHENG Wenlong
,
HUA Huizhong
,
Shanghai Research Institute of Materials
,
Shanghai
,
China ZHANG Rong
,
Lecturer
,
Department of Applied Physics
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China
金属学报(英文版)
The behaviour towards corrosion fatigue of low carbon bainite steel with various microstructures after tempered at different temperatures has been examined. The susceptibility of the steel to corrosion fatigue may be improved by tempering at 300℃.
关键词:
corrosion fatigue
,
null
,
null
,
null
Xiaolei WU
,
Xiangkang MENG
,
Xiyan ZHANG
,
Yanqing YANG and Mokuang KANG(Dept. of Materials Science and Technology
,
401
,
Northwestern Polytech. University
,
Xi'an
,
710072
,
China)
材料科学技术（英）
Thermodynamic analysis for the formation of bainitic ferrite in carbon -depleted region has been conducted. The results show that the driving force of bainitic formation increases with depleting of carbon in parent austenite and with decreasing the transformation temperature. The critical driving force (absolute value) at the Bs temperature is 600-1 200 J / mol, which increases as the mean carbon content of Fe-C alloys increases. The freshly-formed bainitic ferrite has partial supersaturation of carbon, which increases smoothly with decreasing the transformation temperature Therefore, the displacive formation of bainitic ferrite in carbon-depleted region is thermodynamically feasible in the whole temperature range of bainitic reaction.
关键词:
FENG Meibin CHEN Xinzeng HE Jiawen 2nd Automobile Works
,
Shiyan
,
Hubei
,
China. Ningbo University
,
Ningbo
,
Zhenjiang
,
China. Xi'an Jiaotong University
,
Xi'an
,
China.
材料科学技术（英）
The crack initiation behaviour under cyclic compression foy the notched specimen was investigated. It has been found that the cycles for crack initiation increase with the increase of compressive mean stress, and the decrease of stress amplitude. The stress amplitude plays a more important role than the mean stress does. Photoelastic coating and finite element methods were employed to measure and calculate the stress field in the notched part. The resul ts show that the crack initiation under compression is attributed to the tensile stress which may exist during unloadtng. If the true stress state in the notch is compressive, no crack initiates.
关键词:
crack initiation
,
null
,
null
CHEN Zhongmin
,
WANG Naxin
,
SONG Xiaoping
,
WANG XiaotianXi'an Jiaotong University
,
Xi'an
,
China Manuscript received 16 December
,
1993
金属学报(英文版)
The microstructure of Nd_(34)Fe_(60)O_(6) alloy was characterized by means of scanning electron microscope. Auger electron multiprobe, X-ray diffraction, differential thermal analyses and thermomagnetic analyses. It is found that the equilibrium microstructure of the alloy is composed of a Nd_(2)Fe_(17) matrix, an oxygen-containing Nd-rich phase and a Nd-Fe-O ternary ferromagnetic phase (referred to T_(1)). This phase forms via a peritectic reaction between Nd_(2)Fe_(17) and Nd-rich phase at 840 ℃ . Its composition is around Nd_(36)Fe_(54)O_(10) and Curie temperature 180℃ . The X-ray diffraction peaks can be indexed on a tetragonal cell with lattice parameter of a = 0.771nm and c = 2.228nm. This stable phase is believed to be transformed from the metastable phase (A_(1)) in Nd-Fe binary system as a result of oxygen introduced.
关键词:
Nd-Fe-O alloy
,
null
,
null
Hongtao SUN
,
Hongfang WANG
,
Liangying ZHANG and Xi YAO(Electronic Materials Research Laboratory
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China)
材料科学技术（英）
Under the mechanically free and clamped boundary conditions, electromechanical resonances of ceramic multilayer capacitors are calculated using vibration and piezoelectric equations. Multilayer capacitors made of ferroelectric BaTiO3 and Pb(Mg1/3Nb2/3)O3 ceramics have been used to examine the theoretical calculation. Frequency spectra of impedance and phase angle, capacitance and loss tangent of the capacitors under dc bias fields are carefully measured. A sudden change around the resonant frequency is observed in these spectra. A damped resonance indicates a defective capacitor while an undamped resonance is corresponding to defect free.Experimental results suggest that it is possible to use the spectra as a real time nondestructive evaluation method.
关键词:
CAl Yingwen
,
MAO Xiemin
,
LI Jianguo
,
FU HengzhiNorthwestern Polytechnieal University
,
Xi'an
,
China Manuscript received 14 March
,
1994
金属学报(英文版)
Theoretical model for non -equilibrium solidification is constructed with consideration of diffuse interface and multiphase fluctuation. It can he degenerated to Aziz continuous growth model in the case of mono-atomic approximation. for large undercooling, the change of heat capacity should not he neglected and it usually gives an increase in the interface partition coefficient. Solute trapping may happen at a rather slow growth rate compared with that predicted by other models, because the undercooling and structural relaxation ahead of the S/ L interface lowers the interfacial diffusivity to a great extent. Plase fluctuation has two contending effects, decrease in energy barrier and increase in atomic dragging, therefore exerts dual influences on the partition coefficient.
关键词:
diffuse interface
,
null
,
null
CHEN Chujie
,
CHENG Zhengde
,
WANG Lidong
,
HU NaisaiXi'an Jiaotong University
,
Xi'an
,
China
金属学报(英文版)
The fatigue property of the notched part can be improved significantly by introducing compressive residual stress resulting from surface plastic deformation at the notch. The residual stress and strain distributions beneath the notch is predicted by using finite element methed (FEM) of large strain elasto-plastic analysis in this paper. It is investigated wheather the rolling process could be replaced by a plane-strain indenting with a model in the analysis. The effects of material strength, notch radius r. and indentation and depth △h on the distribution of residual stress and strain are discussed. The agreement of predicted and experimental results is good enough.
关键词:
residual stress
,
null
Weidou ZHU and Haicheng GU(Dept. of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China)
材料科学技术（英）
Thin metallic layers (~ 2 μm) of Ni were deposited on polycrystalline Al2O3. ZrO2 and (Ce-TZP)+Al2O3 ceramic substrates. and further irradiated with pulsed excimer (Xeno chloride) laser pulses. The laser energy density was varied from 0.21 to 0.81 J / cm2 to optimize bending strength. For ZrO2 ceramic, it was found that the strength increases from 530 to 753 MPa at 0.51 J / cm2 irradiation. For Al2O3 and (Ce-TZP)+ Al2O3 the fracture strength also increases in varying degree. The causes of strength increment were discussed.
关键词:
