C.L. Mo
,
Y.T. Zhang
,
D.Z. Li
,
Y.Y. Li
金属学报(英文版)
The microstructural banding in steels is often found in hot rolling strips, which plays a very important role in mechanical properties. Much work has been done to investigate how the microstructural banding is formed during hot rolling. In the present study, the microstructure of hot rolling strips was examined in term of optical microscopy and transmission electron microscopy. Electron probe microanalysis ｗａs also used to decide the distribution of microchemical bands, by this means, the phases in these strips were found to be ferrite and pearlite. The average distance between the carbon lamellas in pearlite is about 0.06-0.1μm. It is also shown that microstructural banding in hot rolled carbon steel ｗａs closely related to the segregation of manganese and silicon into those bands. Based on the transformation kinetic, the simulated results pointｅｄ out that the thermodynamic stability of austenite would increase with the increasing of Mn, which led to a decrease of ferrite growth rate. The effect of Mn on the decomposition of austenite is attributed to segregation of Mn atoms along the ferrite/austenite phase boundary which causes a strong solute drag effect. The addition of Mn to steel decreases the activity of austenite, thereby it is beneficial to the formation of non-equilibrium phase, such as degenerate pearlite. The formation of banded structure on the hot rolled process was discussed.
关键词:
pearlite
,
null
,
null
S.Q. Zhou
,
W. Zhao
,
W.H. Xiong
,
Y.N. Zhou
,
null
,
null
,
null
,
null
金属学报(英文版)
Effect of Mo and Mo2C on the microstructure
and properties of Ti(C,N)-based cermets was investigated in this
article. The results have indicated that the weight percentage of Mo
from 5 to 10 can reduce Ti(C,N) grain diameter and thickness of the
rim, and Ti(C,N) grain can be wetted by Ni-Cu-Mo liquid so as to get
small contiguity of Ti(C,N) grain. In that way, the transverse
rupture strength of Ti(C,N)-based cermets has reached
1800—1900 MPa; the fracture toughness has been due to
16—18 MPa m1/2. But 15wt pct Mo was not more effective
on Ti(C,N)-based cermets, because the thickness of the rim becomes
larger. In the circumstance of Mo 2 C, 5 wt pct Mo 2 C was
good for microstructure and properties of Ti(C,N)-based cermets, but
11 wt pct Mo 2 C has resulted in larger contiguity of Ti(C,N)
grain and big Ti(C,N) grain diameter so as to reduce transverse
rupture strength and fracture toughness. So that, the effect of Mo
on Ti(C,N)-based cermets is better than Mo 2 C.
关键词:
Transverse rupture strength (TRS)
,
null
,
null
YANG Xia
,
GUO Shiju
钢铁研究学报(英文版)
Liquidphase enhanced sintering of powder metallurgy (P/M) 316L stainless steel by addition of sintering aids was studied. 2%-8% of prealloyed FeMoB powder with two different particle sizes was added as sintering aids, and the specimens were sintered in vacuum at 1 200-1 350 ℃. The results show that the fine FeMoB powder (5-10 μm) has stronger activated effect. The sintered density increases with the increase in sintering aid content or sintering temperature. Warm compaction has a better effect on the control of dimensional precision of compacts. The prealloyed FeMoB powder deviated from Mo2FeB2 component can also be sintering aid of P/M 316L stainless steel.
关键词:
P/M 316L stainless steel;liquidphase sintering;activated sintering;FeMoB;sintering aid
XU Qikun WANG Dongya Chongqing University
,
Chongqing
,
China XU Qikun
,
Dept.of Metallurgy and Materials Engineering
,
Chongqing University
,
Chongqing
,
Sichuan
,
China
金属学报(英文版)
The transformation process and the products of long term isothermal transformation around the kinetic B_s temperature(the bay temperature in TTT diagram)in Fe-C-Mo alloys have been investigated.It was found that,at the final stage of intermediate transformation,a kind of granular structure formed accompanying the growth of bainitic ferrite.In comparison with the carbide Mo_2C in the bainitic ferrite plates or blocks,the carbide m granular eutectoid has been determined to be cementite containing a tiny bit of molvbdenum,(Fe,Mo)_3C.
关键词:
allot Fe-C-Mo
,
null
,
null
,
null
胡锐
,
李金山
,
李进学
,
周尧和
中国有色金属学报
分析了C/Cu复合材料的界面润湿特性及多种润湿涂层的性质. 选择Mo2C+Mo作为C/Cu复合材料的润湿涂层, 研究了该涂层对真空液相浸渗C/Cu复合材料界面润湿特性的影响. 结果表明, 传统金属Cu涂层在浸渗温度下失效, 而Mo2C+Mo涂层在液相浸渗温度下较稳定, 能显著提高C/Cu界面润湿性, 有效改善界面结合, 并促进液相浸渗复合过程的进行.
关键词:
C/Cu复合材料
,
涂层
,
液相浸渗
X.R. Wang
材料科学技术（英文）
This paper has constructed two kinds of atomic and electronic models for hexagonal β-Mo2C and orthorhombic α-Mo2C. The optimized lattice parameters, elastic constant matrixes and overlap population for Mo2C crystal cells have been obtained to realize the characterization of the hardness and melting point of the two structures by the first-principles plane wave pseudo potential method based on the density functional theory. The results reveal that the calculated lattice parameters of the Mo2C crystal cells agree with the experimental and other calculated data. The calculated melting point/hardness are 2715 K/11.38 GPa for β-Mo2C and 2699 K/10.57~12.67 GPa for α-Mo2C, respectively. The calculated results from the density of states (DOS) demonstrate that the hybridization effect between Mo-3d and C-2p states in α-Mo2C crystal cell is much
stronger than that in β-Mo2C one.
关键词:
First-principle; Mo2C
吴东江
,
范聪
,
刘士博
,
马广义
,
郭玉泉
,
牛方勇
,
郭东明
稀有金属
使用Nd:YAG连续激光对Hastelloy C-276/316L薄板进行异质焊接实验,分析不同激光偏移量下焊缝元素含量变化规律,借助极化曲线、电化学阻抗谱研究不同激光偏移量下焊缝在盐酸溶液中的抗蚀性能.结果表明:调节激光偏移量Fe、Ni和Mo含量变化明显,而Cr含量无明显变化;当激光向Hastelloy C-276偏移0.1～0.3 mm时,焊缝中主要元素含量变化较小,腐蚀电压、电荷转移电阻最大,腐蚀电流密度最小,焊缝腐蚀趋势、腐蚀速率最小,焊缝抗蚀性能较好;当激光向316L偏移0至0.2 mm时,焊缝中Fe元素逐渐增加,Ni、Mo元素含量逐渐下降,焊缝的腐蚀电压、电荷转移电阻递减,腐蚀电流密度递增,焊缝的腐蚀趋势、腐蚀速率逐渐增大,焊缝抗蚀性逐渐减弱.
关键词:
Hastelloy C-276/316L
,
激光异质焊接
,
电化学腐蚀
Physica Status Solidi a-Applications and Materials Science
A three-dimensional molybdenum-carbides/graphite network formed by superconducting MoC/Mo(2)C nanograins embedded in a magnetic graphite matrix was fabricated. The temperature dependence of magnetization of the MoC/Mo(2)C nanocomposites indicates that the superconducting transition temperatures (T(c)) of Mo(2)C and MoC nanocrystals are 8 K and 11.5 K, respectively. These transition temperatures are lower than those of their corresponding bulk counterparts, due to the detrimental influence of magnetic graphite. The magnetization influenced by edge barrier and magnetic graphite are investigated for the MoC/Mo(2)C nancomposites embedded in the magnetic graphite matrix. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
关键词:
high-temperature superconductors;surface barriers;films;irreversibility;nanotubes;arrays
GUO Jin-hua
,
GAO Zhen
,
NI Xiao-jun
,
et al
钢铁研究学报(英文版)
Fe55Ni2Cr12Mo10B6C13Y2，Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4mm were produced by copper mold casting. The role of alloying additions (Ni, Cu or Nb) on corrosion resistance of Fe55Nb2Cr12Mo10B6C13Y2, Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys were studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys can be cast into bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 amorphous alloys with passive potential about 1500 mV exhibit good corrosion resistance in 5 % NaCl solution and 1 mol/L HCl solution. The passive current density of the alloy with Ni addition is lower than other alloys. EIS results only show one impedance element. Amorphous alloy Fe55Ni2Cr12Mo10B6C13Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.
关键词:
amorphous;polarization curve;electrochemical impedance spectroscopy
来忠红
,
朱景川
,
全在昊
,
尹钟大
稀有金属材料与工程
在C/C复合材料表面采用熔浆法制备Mo-Si系涂层的烧结过程中通入氮气,开发了Si3N4-MoSi2/Si-SiC(Mo-Si-N系)多层抗氧化涂层,并初步考察了涂层的抗氧化性能.结果表明,多层涂层的致密性主要受制于起始氮化温度.只有在Si熔点以上通入氮气,才能获得致密无缺陷的涂层.多层涂层的底层为SiC,外层为Si3N4,中间层为MoSi2/Si.这种多层涂层的抗氧化性能与涂层中MoSi2的含量有关;MoSi2含量为30%(体积分数,下同)和40%时,与真空中合成的Mo-Si涂层相比,高温抗氧化性能显著改善,抗氧化温度提高到1400℃～1450℃.
关键词:
C/C复合材料
,
抗氧化涂层
,
Si3N4
,
MoSi2/Si
,
SiC
