Philosophical Magazine A最新文献_第4页

Computer simulation of the fracture of carbon nanotubes in a hydrogen environment 碳纳米管在氢环境中断裂的计算机模拟

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240433

L. Zhou, S. Shi

引用次数: 3

Scaling relations for crack-tip plasticity 裂纹尖端塑性的标度关系

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240432

A. Hartmaier, P. Gumbsch

{"title":"Scaling relations for crack-tip plasticity","authors":"A. Hartmaier, P. Gumbsch","doi":"10.1080/01418610208240432","DOIUrl":"https://doi.org/10.1080/01418610208240432","url":null,"abstract":"Abstract The fracture toughness of semibrittle materials such as bcc transition metals or semiconductor crystals strongly depends on loading rate and temperature. If crack-tip plasticity is considered to be thermally activated, a strong correlation between these quantities is expected. An Arrhenius-like scaling relation between the loading rate and the brittle-to-ductile transition temperature has already been reported. In the present work, two-dimensional discrete dislocation dynamics simulations of crack-tip plasticity are employed to show that the different combinations of loading rates and temperatures which yield the same fracture toughness are indeed correlated by a scaling relation. This scaling relation is closely related to the law used to describe dislocation motion. A strong correlation between loading rate and temperature is found in the entire temperature regime in which crack-tip plasticity is controlled by dislocation mobility. This shows the importance of dislocation mobility for fracture toughness below the brittle-to-ductile transition and for the transition itself. The findings of our simulations are consistent with experimental data gathered on tungsten single crystals and suggest that non-screw dislocations are dominating crack-tip plasticity in the semibrittle regime of this material.","PeriodicalId":114492,"journal":{"name":"Philosophical Magazine A","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129697454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 23

Effects of hydrostatic pressure on the flow and fracture of a bulk amorphous metal 静水压力对大块非晶金属流动和断裂的影响

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240453

J. Lewandowski, P. Lowhaphandu

{"title":"Effects of hydrostatic pressure on the flow and fracture of a bulk amorphous metal","authors":"J. Lewandowski, P. Lowhaphandu","doi":"10.1080/01418610208240453","DOIUrl":"https://doi.org/10.1080/01418610208240453","url":null,"abstract":"Abstract The flow and fracture behaviour of a Zr-Ti-Ni-Cu-Be bulk amorphous metal have been determined in tension and compression at room temperature with levels of superimposed hydrostatic pressure ranging from 0.1 to 700 MPa. Metallographically polished cylindrical specimens tested in uniaxial tension and compression were utilized in the high pressure tests, while polished cylindrical torsion specimens were tested at 0.1 MPa (i.e. atmospheric pressure) in order to approach conditions of pure shear. All the tension and torsion tests, regardless of the level of superimposed pressure, exhibited linear elastic failure, as did the compression tests conducted with low levels (e.g. less than 450 MPa) of pressure. At the highest pressures (i.e. 450 MPa or higher), the compression tests exhibited elastic-perfectly plastic behaviour and an increase in the compressive elongation to fracture. The flow stress and fracture stress were not significantly affected by the superposition of pressure as failure occurred in shear, indicative of pressure-independent behaviour over the range tested. However, a change in fracture plane angle was detected. Tensile fracture surfaces were oriented at 50–59°; compression fracture surfaces were oriented at 40°. The flow and fracture behaviours were analysed in terms of a Mohr-Coulomb criterion of the form τc = 950 MPa - 0.038ω;n over the range of stress states examined. The results are discussed in the light of the various yield criteria and the flow and fracture theories provided for amorphous metallic systems.","PeriodicalId":114492,"journal":{"name":"Philosophical Magazine A","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123560130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 177

Local disordering and reordering phenomena induced by mobile dislocations in short-range-ordered solid solutions 短程有序固溶体中由移动位错引起的局部无序和重有序现象

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208239633

F. Pettinari-Sturmel, M. Jouiad, H. Kirchner, N. Clément, A. Coujou

引用次数: 12

Brittle-to-ductile transition and slip band structure in ionic crystals 离子晶体的脆性-延性转变和滑移带结构

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240436

N. Narita, Y. Takahara, K. Higashida

{"title":"Brittle-to-ductile transition and slip band structure in ionic crystals","authors":"N. Narita, Y. Takahara, K. Higashida","doi":"10.1080/01418610208240436","DOIUrl":"https://doi.org/10.1080/01418610208240436","url":null,"abstract":"Abstract The interrelation between the brittle-to-ductile transition (BDT) and slip structure has been examined using NaCl and KCl crystals. In pre-cracked crystals of NaCl and KCl having a ⟨100⟩ axis, the fracture toughness K*ic increases above 300 and 220 K, and the BDT occurs at 510 and 430 K respectively. Scale-like wavy lines are revealed ahead of a pre-crack on etched fracture faces of NaCl tested above 300 K. As the temperature increases, the step height and density of the lines are increased but the lines are more restricted near the pre-crack front. In NaCl and KCl crystals without pre-cracking, the critical resolved shear stress for {110} main slip is very low above 77 K, while that for {010} slip markedly increases as temperature decreases below 500 and 300 K respectively. In ⟨100⟩-uniaxial tests for non-pre-cracked NaCl crystals, the BDT takes place at around 380 and 480 K at strain rates of 5.5 × 10−6 and 5.5 × 10−5s−1 respectively. Above the BDT temperature, wavy slip lines are abundantly produced by the marked operation of cross-slip. A mechanism based on the crack tip shielding through the cross-slip of dislocations along a crack front is proposed to explain observed crack face morphology as well as the BDT in ionic crystals of NaCl structure.","PeriodicalId":114492,"journal":{"name":"Philosophical Magazine A","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123503771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Micromechanical models and the statistical analysis of fracture and fracture toughness 断裂和断裂韧性的微观力学模型和统计分析

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240455

J. Knott

引用次数: 7

Effect of strong chemical short-range order in ternary liquid alloys on dynamic liquid-crystal interface energy; consequence for crystalline nucleation 三元液态合金中强化学短程有序对动态液晶界面能的影响结晶成核的结果

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208239628

P. Desré, N. Eustathopoulos

{"title":"Effect of strong chemical short-range order in ternary liquid alloys on dynamic liquid-crystal interface energy; consequence for crystalline nucleation","authors":"P. Desré, N. Eustathopoulos","doi":"10.1080/01418610208239628","DOIUrl":"https://doi.org/10.1080/01418610208239628","url":null,"abstract":"Abstract Since the discovery of bulk metal glasses obtainable by moderate quenching rates from the liquid state, more attention has been given to nucleation phenomena in multicomponent liquid alloys. Among the parameters controlling the frequency of nucleation in the highly supercooled range of the melt, the liquid-crystal interface energy is known to be particularly significant. Almost no experimental data on these energies are available when bulk glass-forming liquid alloys are involved. This work is focused on the study of the effect of liquid-crystal partitioning and of chemical short-range order (CSRO) in the liquid alloy on the dynamic liquid-crystal interface energy. Application to ternary liquid glass formers Zr-Cu-Pd is presented. The broken-bonds method is applied to evaluate the excess interface energy between binary and ternary liquid-crystal systems. The Warren-Cowley order parameters, used to quantify CSRO in the liquid alloy, are evaluated on the basis of the Guggenheim quasichemical model. A specific ternary effect on the dynamic liquid-crystal interface energy is demonstrated; its consequence for crystalline nucleation is discussed.","PeriodicalId":114492,"journal":{"name":"Philosophical Magazine A","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130383671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Oxidation behaviour and strength degradation of a Yb2O3−SiO2−doped hot-pressed silicon nitride between 1200 and 1500°C Yb2O3 - SiO2掺杂的热压氮化硅在1200 ~ 1500℃之间的氧化行为和强度退化

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208239632

Shuqi Guo, N. Hirosaki, T. Nishimura, Yoshinobu Yamamoto, M. Mitomo

引用次数: 21

Crack tip dislocations in silicon characterized by high-voltage electron microscopy 高压电子显微镜对硅裂纹尖端位错的表征

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240439

K. Higashida, N. Narita, M. Tanaka, T. Morikawa, Y. Miura, R. Onodera

引用次数: 20

Mechanical behaviour and dislocation arrangements of cyclically deformed silicon single crystals 循环变形硅单晶的力学行为和位错排列

Philosophical Magazine A Pub Date : 2002-11-01 DOI: 10.1080/01418610208240440

M. Legros, A. Jacques, A. George

引用次数: 5