W.N.Liu 1)
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M.N.Fang 2)
,
J.Xing 1) and Y.W.Liu 3) 1) Department of Mechanical Engineering
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Changchun Institute of Optics and Fine Mechanics
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Changchun 130022
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China 2) Changchun Institute of Post and Telecommunications
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Changchun 130022
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China 3) Changchun Institute of Optics and Fine Mechanics
,
Changchun 130022
,
China
金属学报(英文版)
In this paper, we describe the laser heat-treating experiment results of three kind tool high-speed steel test samples. After laser quenching and tempering of three kinds of annealed tool high speed steel (W18Cr4V, W9Mo3Cr4V1, W6Mo5Cr4V2) test samples, we used microhardness-measure to test the samples and analyzed such problems as the hardness and depth of hardening quenching layer. Furthermore, after laser quenching and tempering of the quenched and three time tempered high speed steel (W18Cr4V) and its hardness analyzing, we got lase quenching's different results of the samples under different initial heat treating.
关键词:
high-speed steel
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null
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null
K.K.Bamzai
,
P.N.Kotru
,
B.M.Wanklyn
材料科学技术（英文）
Results on fracture mechanics and crack propagation have been obtained, making use of Vickers microhardness studies on two different crystallographic planes [(110) and (001)] of flux grown erbium aluminate crystals in the load ranging from 10 similar to 100 g. The variation of microhardness with load which is best explained by Hays and Kendall's law leads to the load independent values of hardness. Classification of cracks is dealt with and it is reported that the transition from Palmqvist to median types of cracks occurs at higher loads. The values of fracture toughness (K-C), and brittleness index (B-i) are calculated using median types of cracks.
关键词:
B.W. Wang
,
H. Shen
金属学报(英文版)
Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.
关键词:
solar selective thin film
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null
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null
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null
F. Zhang1)
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X. D. Sun1)
,
J. You2)
,
Z. Zhang2)
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L. X. Ding3)and Y. M. Wang3)1) School of Materials and Metallurgy
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Northeastern University
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Shenyang 110006
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China2) Liaoning Analyzing and Testing Research Center
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Shenyang 110015
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China3) Department of Materials
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School of Mechanical Engineering
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Shenyang University
,
Shenyang 110044
,
China
金属学报(英文版)
Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hcan be synthesized by adding a m m oniu m alu m inu m sulfate solution torapidly stirred a m moniu m hydro - carbonate solution at a tem perature of 30 ℃. A A C Hcantransfor m to α Al2 O3 co m pletely by calcining at 1100 ℃ for 1 hour , and the obtained po w ders , with a particle size of 100 n m , can be sintered to 98 99 % relative density at 1500 ℃for 2 hours .
关键词:
a m moniu m alu m inu m carbonate hydroxide
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null
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null
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null
MA Zongyi YAO Zhongkai Harbin Institute of Technology
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Harbin
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China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
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null
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null
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null
Yang LUO
材料科学技术（英文）
Due to continued growth in key markets, a broadening of application base and performance improvements, the market demands of NdFeB magnet increased steadily in 1998, and the global output of sintered NdFeB magnet exceeded 10,000 t, in spite of the economic recession in Asia. In 1998 China produced 3,850 t sintered NdFeB block magnet, with an annual growth rate of +22% over the output in 1997.
关键词:
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
Creep behaviour of aluminium strengthened by fine aluminium carbide particles and reinforced by silicon carbide particulates is investigated. For comparison, the results for two dispersion strengthened (DS) AlC alloys denoted DS AlCl and DS AlC2 are presented. (C1 and C2 mean the contents of carbon in wt% which define the volume fractions of Al4C3 particles in DS AIC alloys as well as in SiC/AlC composite matrices). The volume fraction of SiC particulates in composites, denoted SiC/AlCl, SiC/AlC2 and SiC/AlC3, was used to 10 vol.%. The creep in both DS AIC alloys as well as in SiC/AlC composites is associated with relatively high true threshold stress sigma(TH). The linear regression analysis showed that the true stress exponent of minimum creep strain rate of 8 should be preferred to that of 5. The creep strain rate was found to be controlled by lattice diffusion in the matrix metal-aluminium. The creep strength of the SiC/AlC composites increasing with the volume fraction of Al4C3 particles is entirely due to the effect of this fraction on the threshold stress. This is not the case of DS AlC alloys. The difference of the creep strength in SiC/AlC composites and the respective DS AlC alloys could be accounted for by the load transfer effect. The athermal detachment of dislocations from fine Al4C3 (and Al2O3) particles dispersed in the composite matrix is considered as the creep strain rate controlling process. (C) 1999 Published by Elsevier Science S.A. All rights reserved.
关键词:
DS SiC AlC composites;creep;threshold stress;stress exponent;diffusion control;high-temperature creep;metal-matrix composites;dislocation climb;hard;particles;al composite;alloy;model
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
Creep behaviour of aluminium strengthened by fine aluminium carbide particles and reinforced by silicon carbide particulates is investigated. For comparison, the results for two dispersion strengthened (DS) A1C alloys denoted DS A1C1 and DS A1C2 are presented. (C1 and C2 mean the contents of carbon in wt% which define the volume fractions of Al4C3 particles in DS A1C alloys as well as in SiC/A1C composite matrices). The volume fraction of SIC particulates in composites, denoted SiC/A1C1, SiC/A1C2 and SiC/A1C3, was fixed to 10 vol.%. The creep in both DS A1C alloys as well as in SiC/A1C composites is associated with relatively high true threshold stress sigma(TH). The linear regression analysis showed that the true stress exponent of minimum creep strain rate of 8 should be preferred to that of 5. The creep strain rate was found to be controlled by lattice diffusion in the matrix metal-aluminium. The creep strength of the SiC/A1C composites increasing with the volume fraction of Al4C3 particles is entirely due to the effect of this fraction on the threshold stress. This is not the case of DS A1C alloys. The difference of the creep strength in SiC/A1C composites and the respective DS A1C alloys could be accounted for by the load transfer effect. The athermal detachment of dislocations from fine Al4C3 (and Al2O3) particles dispersed in the composite matrix is considered as the creep strain rate controlling process. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
high-temperature creep;metal-matrix composites;dislocation climb;hard;particles;al composite;alloy;model
