材料期刊网

EFFECT OF SLIP ORIENTATION ON STRESS RESPONSE,INTERNAL FRICTION AND ULTRASONIC ATTENUATION DURING CYCLIC DEFORMATION IN Al SINGLE CRYSTALS

XIA Yuebo ZHANG Tianyi State Key Laboratory for Fatigue and Fracture of Materials , Institute of Metal Research , Academia Sinica , Shenyang , ChinaFEI Guangtao ZHOU Xing Laboratory of Internal Friction and Defects in Solids , Institute of Solid State Physics , Academia Sinica , Hefei , China Associate Professor , Institute of Metal Research , Academia Sinica , Shenyang 110015 , China

金属学报(英文版)

The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indicate that the value of cyclic stress σ,internal friction Q~(-1)and ultrasonic attenuation △α depend obviously on the slip orientation.There are large differences in above three parameters for different slip orientation Al crystals.In early stage of fatigue life,σ and △α increase and Q~(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q~(-1)and σ get the valley and the peak,respectively,at same cycles.

关键词: crystal orientation , null , null , null , null , null

ANELASTIC RELAXATIONS ASSOCIATED WITH LOCAL DISORDERING AT GRAIN BOUNDARIES

CHENG bolin GE Tingsui (T.S.Ke) Laboratory of Internal Friction and Defects in Solids , Institute of Solid State Physics , Academia Sinica , Hefei , China Professor Laboratory of Internal Friction and Defects in Solids , Institute of Solid State Physics , Academia Sinica , Hefei , 230031

金属学报(英文版)

Internal friction and micro-creep measurements were performed with high-purity aluminium bamboo-crystal specimens.The relaxation strength was found to decrease with the decrease of temperature and became zero at about 0.4 T_m(T_m is the melting temperature).This re- flects the occurrence of local disordering in the bamboo boundary region at this temperature. This result conforms to the picture of grain-boundary disordering constructed by atomic simulation studies.

关键词: Grain boundary disordering , null , null , null

EFFECT OF AGING ON INTERNAL FRICTION,ELASTIC MODULUS AND MECHANICAL PROPERTIES OF TERNARY Mn-Cu-Al ALLOYS

YI Huchun GE Tingsui (T.S.Ke) Institute of Solid State Physics , Academia Sinica , Hefei , China GE Tingsui , Professor , Laboratory of Internal Friction and Defects in Solids , Institute of Solid State Physics , Academia Sinica , Hefei , China

金属学报(英文版)

Internal friction and elastic modulus of ternary Mn-Cu-Al alloys containing 56—60 wt-% Mn,0-3.59 wt-% Al were measured with acoustic frequency,1 kHz,in the tempera- ture range of-150 to 150℃.It was found that when the specimen was aged in the temperature range under the spinodal curve within the miscibility gap(400—500℃),the internal fric- tion increases with an increase of the aging time and reaches a maximum value at a certain ag- ing time which is shorter with a higher aging temperature.Two internal friction peaks which did not appear before the aging were observed above room temperature after a definite aging time.These are respectively the martensitic tranformation peak and the relaxation peak orig- inating from the stress-induced movement of the twin boundaries.The former peak shifts to- ward higher temperatures with an increase of the aging time,whereas the relaxation peak ap- pearing at 15℃,is independent of the aging time and temperature.The activation energy as- sociated with the relaxation peak was found to be 0.56 eV which is about the same as that of the relaxation peak in binary alloy containing 90 wt-% Mn.It was also found that the hardness,strength and the brittleness of the specimen increase when aged below the spinodal curve within the miscibility gap.The addition or Al enhances the strength but reduces the in- ternal friction of the specimen.A choice of suitable aging time and temperature can give an optimum compromise of high strength and high internal friction.Analysis of experimental re- sults suggests that spinodal decomposition leads to Mn-rich zones in the specimen and thus causes the phase transformation and the change of mechanical properties of the specimen.

关键词: internal friction , null , null , null , null

ON DEGRADATION OF DUCTILITY INDUCED BY HYDROGEN IN MEDIUM CARBON STEELS

DU Jiaju TONG Shihua Institute of Solid State Physics , Academia Sinica , Hefei , China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A226—A228 , Associate Professor , Institute of Solid State Physics , Academia Sinica , Hefei , China

金属学报(英文版)

Optical microscope,SEM and IMMA investigation show that a strong interaction between hydrogen and calcium aluminate inclusions containing MgO may occur in medium carbon steels.This causes the hydrogen accumulating around the inclusions and reducing the ductility of the steel.

关键词: hydrogen , null , null

CHARACTERISTICS OF INTERNAL FRICTION AND MODULUS ASSOCIATED WITH NON-EQUILIBRIUM DIFFUSION-TYPE PHASE TRANSFORMATION IN EUTECTOID Al-Zn ALLOY

ZHU Xianfang ZHANG Lide Institute of Solid State Physics , Academia Sinica , Hefei , China Research Assistant , Institute of Solid State Physics , Academia Sinica , Hefei , China

金属学报(英文版)

The characteristics of the low frequency internal friction and the modulus effect associated with the non-equilibrium spinodal pretransformation and the following discontinuous trans- formation was investigated in an as-quenched eutectiod Al-Zn alloy.It was observed that the loss of the stability in the lattice,which corresponded to the large-amplitude long-wavelength static concentration wave in the non-equilibrium spinodal pretransformation,did not induce any effect of localized soft modulus.Although there are two aging internal friction peaks in phase transformation which correspond to the appearance and disappearance of the coherency in spinodal pretransformation and the maximum of the interface area in the discontinuous transformation respectively,the effect of localized soft modulus did not take place yet.

关键词: spinodal pretransformation , null , null , null

INTERNAL FRICTION AND MODULUS DEFECT ASSOCIATED WITH THE MICROCRACKS IN MATERIALS

Q.F.Fang Laboratory ofInternal Friction and Defectsin Solids , Institute of Solid State Physics , The Chinese Academy of Sciences , Hefei230031 , China

金属学报(英文版)

Inthis paper, theinvestigation of applying internalfriction ( ultrasonic attenuation) andmodulus defect(ultrasonic velocity change) tostudy the variation of dislocation density andlooplength withcycle numberintheearly fatiguestageisreviewed. On this basis,thecon ceptof characterization of fatigue microcrackformation and propagation assessed bythe mea surementofinternalfriction and dynamicalelastic modulusissuggested. Theanalyticalex pressionoftheinternalfriction and modulus defect associated with microcracksiscalculated underthe assumptionthatthe mechanicalenergy dissipation iscaused by the mutualfriction betweentheoppositefacesofthe microcrack.

关键词: internalfriction , null , null

SUPERPLASTICITY AND SOLID STATE BONDING OF TITANIUM ALLOYS

R. Ya. Lutfullin , O.A. Kaibyshev , R.V. Safiullin , O.R. Valiakhmetov and M.H. Mukhametrahimov Institute for Metals Superplasticity Problems , Russian Academy of Sciences , Ufa 450001 , Russia

金属学报(英文版)

Experimental results related to solid state weldability of superplastic titanium alloys are presented. A correlation between superplastic flow and enhanced solid state weldability was established. It has been experimentally shown that a drop in the lower superplastic flow temperature with decreasing mean grain size provides an opportunity to decrease the temperature at whicmethods for titanium alloys.

关键词: superplasticity , null , null

Solid state reaction of Mg with Ni under high pressure

High Pressure Research

Solid state reaction of Mg with Ni was processed under static high pressure and nanocrystalline Mg2Ni was obtained. An unknown phase was also formed at lower temperature. The relation between the mean grain size of Mg2Ni and the synthetizing pressure is given, and its mechanism is discussed.

关键词: solid state reaction;high pressure;nanocrystalline;Mg2Ni;mean grain;size;unknown phase;ab(2)-type intermetallic compounds;crystal-structure

Lattice instability in the solid-state amorphization of Fe(Al) solid solutions by mechanical alloying

Physical Review B

Metastable Fe100-xAlx alloys have been formed by ball milling of elemental Fe and Al powders: supersaturated body-centered-cubic solid solutions for x less than or equal to 70, and an amorphous phase for x > 70. Quantitative x-ray-diffraction measurements show that the total root-mean-square displacement (rms) and the static rms in the Fe100-xAlx solid solutions increase significantly with increasing Al content, The total rms at the instability point, however, reaches only 6.8% of the nearest-neighbor distance and is far below the critical value predicted by the Lindemann melting criterion, suggesting that the Lindemann melting criterion is not applicable for the solid-state amorphization. Instead. the Debye temperature of the supersaturated Fe100-xAlx alloys was observed to drop by similar to 22% at the point of amorphization, implying a corresponding softening in the average shear modulus of similar to 40%, which agrees with the microhardness measurements. These results strongly support the empirical elastic instability criterion For the solid-state amorphization process.

关键词: to-glass transition;crystal;transformation

Solid-state and liquid-state interfacial reactions between Sn-based solders and single crystal Ag substrate

Journal of Alloys and Compounds

Growth kinetics and interfacial morphologies of the intermetallic compounds (IMCs) between single crystal Ag and Sn-4Ag, Sn-3Cu and Sn-37Pb solders were investigated by solid-state aging at 160 degrees C and liquid-state aging at 260 degrees C. Isothermal equation of chemical reaction and phase diagrams were used to explain the effects of Ag, Cu and Pb on the growth kinetics of IMCs under solid-state and liquid-state aging conditions. The diffusion coefficients for the three solder joints of Sn-4Ag/Ag, Sn-3Cu/Ag and Sn-37Pb/Ag were calculated after solid-state and liquid-state aging. It is found that Pb can effectively retard the growth of IMCs during liquid-state aging but has little influence on the growth rate of IMCs during the solid-state aging. Some local small cracks were frequently observed in the Cu(6)Sn(5) particles near interfaces of the Sn-3Cu/Ag solder joints after solid-state aging for several days. However, there were no such local small cracks when solders or interfaces did not contain the Cu(6)Sn(5) particles after the same aging time. (C) 2008 Elsevier B.V. All rights reserved.

关键词: Ag single crystal substrate;Lead-free solder;Intermetallic compounds;(IMCs);Growth kinetics;Local cracks;lead-free solders;electroless ni(p) metallization;intermetallic;compound;cu-sn;joints;ni;bi;nanoindentation;microstructure;wt.percent