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991.
992.
基于作者以前提出的粉喷桩新型固化剂, 在现场进行桩体施工。采用双层单动法钻孔取芯, 对取芯进行强度试验。分析和讨论了现场取芯与室内试块的强度, 为推广采用新型固化剂奠定一定的基础, 对粉喷桩设计和施工亦有一定的参考价值。 相似文献
993.
994.
J. A. Kittl P. G. Sanders M. J. Aziz D. P. Brunco M. O. Thompson 《Acta Materialia》2000,48(20):4797-4811
The interface response functions for rapid solidification of a non-dilute binary alloy were measured in the regime of partial solute trapping, where substantial discrepancies exist among predictions for the interfacial undercooling in various models. We used pulsed laser melting of Si-As on insulating substrates to enforce planar solidification spanning the velocity range 0.2–2 m/s. Nanosecond-resolution electrical measurements of the time-dependent melt depth and of the electrical resistivity of a buried Pt thin film thermometer permitted us to determine the solidification velocity and the temperature of the crystal/melt interface. With composition–depth profile measurements we also determined the nonequilibrium partition coefficient. The measured velocity-dependence of the interface temperature and partition coefficient are quantitatively consistent with the continuous growth model without solute drag of M. J. Aziz and T. Kaplan [Acta Metall. 36, 1335 (1988)] and are qualitatively and quantitatively inconsistent with all models exhibiting a significant solute drag effect. Elements of a potential explanation are proposed using the solute drag model of M. Hillert and B. Sundman [Acta Metall. 24, 731 (1976)] to investigate the origin of the solute drag effect in terms of irreversible processes occurring within a diffuse interface. 相似文献
995.
996.
SUN LilingInstitute of Metal Research Chinese Academy of Sciences Shenyang ChinaWU QiShenyang College of Technology Shenyang ChinaZHANG Zhiya HU ZhuangqiInstitute of Metal Research Chinese Academy of Sciences Shenyang China 《金属学报(英文版)》1994,7(1):23-26
The effect of trace element B on microstructure of directionally slidified new type Co-base superalloy is studied systematically in this paper.It is found that the addition of B makes the incipient melting temperature of the alloy decline remarkably.Compared withthe alloy having a boron contenl of 0.05%,the incipient melting temperature of the alloywith 0.7% B decreases by 197℃.The primary and secondary dendrite arm spacings in-crease and the volume fraction of interdendritic carbides with fine microstructure becomesbigger with the enhancement of boron content.When the alloy is with 0.7wt%B,M_3B_2 precipitates in the interdendrites. 相似文献
997.
NING Yuantao ZHOU Xinming DAI Hong Institute of Precious Metals Kunming Yunnan China 《金属学报(英文版)》1992,5(11):327-333
The splat folis of Al-RE(RE=Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Er and Yb)binary alloys of 0.04—0.06 mm thickness were made by are-melting and hammer-anviltechnique,the.cooling rate is in 10~6 K/s order of magnitude.The metastable extendedsolid solubilities of these RE elements have been evaluated by measurements of the latticespacings of the rapidly solidified(RS)Al-RE alloys,they are 0.4,0.15,0.21,0.21,0.3,0.5,0.1,0.6,0.65,0.7,0.75,0.2 at.-% for above individual RE clements,respectively.Thesecondary phase in RS Al-RE alloys were identified to be Al_4RE for alloys containinglight RE and Eu elements and Al_3 RE for alloys containing heavy RE and Y elements.Some factors influencing the extension of solid solubility of Al-RE alloy were discussed. 相似文献
998.
The stress-strain relation for cast low alloy carbon steel at solidification temperature hasbeen examined by the authors' own desingned apparatus for rheological propertiesmeasurement.The rheology model,the stress-strain constitutive equation and the rheologicalparameters therefrom of the cast steel were proposed.Thus the theoretical basis and calcula-ting data for computerized s#nulation on the stress-strain relation and thermal cracking ofthe cast steel were suggested. 相似文献
999.
EFFECTOFGRAVITYFIELDONSOLIDIFICATIONBEHAVIOROFSTEELINGOT¥CHENWeide;ZHENGXianshu;JINJunze(DalianUniversityofTechnology,Dalian,... 相似文献
1000.
LI Jianguo MAO Xiemin FU Hengzhi National Laboratory of solidification Technology Northwestern Polytechnical University Xi''''an China Lecturer.Faculty No. Northwestern Polytechnical University Xi''''an China 《金属学报(英文版)》1991,4(1):71-74
The interface morphologies and microstruetures of the directionally solidified Ni-5wt-% Cualloy during dendrite-to-cell transition at high growth rates have been investigated with anewly developed apparatus for unidirectional solidification with the temperature gradient atthe solid/liquid interface higher than 1000 K/cm.The results show that in the vicinity ofdendrite-to-cell transition point,the well developed sidebranches become shrivelled with theincrease of growth rate and disappear at the dendrite-to-cell transition,and the primaryspacing decreases simultaneously.Moreover,the length of mushy zone decreases greatly dur-ing the dendrite-to-cell transition.Cells obtained at high growth rates have very similarmorphologies to those at low growth rates,but with much smaller cell spacings andunsmoothed cell walls which may be attributed to the different stability conditions of the cellwalls at low and high growth rates respectively. 相似文献