Acta Metallurgica最新文献_第9页

Simulation of grain-size distributions in nucleation and growth processes 成核和长大过程中晶粒尺寸分布的模拟

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90302-7

B. Lorenz

引用次数: 14

Elastic moduli of polycrystalline, high-temperature binary intermetallic compounds 多晶高温二元金属间化合物的弹性模量

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90314-3

R.L. Fleischer, R.S. Gilmore, R.J. Zabala

引用次数: 31

Slip patterns made by sphere indentations on single crystal MnZn ferrite 单晶MnZn铁氧体上球形压痕的滑移模式

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90294-0

A.Broese Van Groenou, S.E. Kadijk

引用次数: 24

Friction stress for carbon composite and carbon yarn during high temperature creep 碳复合材料与碳纱在高温蠕变过程中的摩擦应力

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90300-3

G. Sines , Z. Yang , B.D. Vickers

引用次数: 5

Role of interfacial grain-bridging sliding friction in the crack-resistance and strength properties of nontransforming ceramics 界面晶间桥接滑动摩擦对非相变陶瓷抗裂和强度性能的影响

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90299-X

S.J. Bennison , B.R. Lawn

{"title":"Role of interfacial grain-bridging sliding friction in the crack-resistance and strength properties of nontransforming ceramics","authors":"S.J. Bennison , B.R. Lawn","doi":"10.1016/0001-6160(89)90299-X","DOIUrl":"10.1016/0001-6160(89)90299-X","url":null,"abstract":"<div><p>A grain-bridging model of crack-resistance or toughness (R-curve, or T-curve) properties of nontransforming ceramics is developed. A key new feature of the fracture mechanics treatment is the inclusion of internal residual (thermal expansion mismatch) stresses in the constitutive stress-separation relation for pullout of interlocking grains from an embedding matrix. These internal stresses play a controlling role in the toughness properties by determining the scale of frictional tractions at the sliding grain-matrix interface. By providing a physical account of the underlying micromechanics of the bridging process the analysis allows for predetermination of the material factors in the constitutive relation, thereby reducing parametric adjustments necessary in fitting the theoretical toughness curve to experimental data. The applicability of the model is illustrated in a case study on indentation-strength data for a “reference” polycrystalline alumina with particularly strong T-curve characteristics. From theoretical fits to these data the constitutive relation, and thence the entire T-curve, can be deconvolved. This “parametric calibration”, apart from demonstrating the plausibility of the model, allows for quantitative predictions as to how the toughness and strength characteristics of ceramics depend on such microstructural variables as grain size and shape, grain boundary energy, level of internal stress and sliding friction coefficient. An indication of this predictive capacity is provided by a preliminary calculation of the grain-size dependence of strength, using some existing data for other aluminas as a basis for comparison.</p></div>","PeriodicalId":6969,"journal":{"name":"Acta Metallurgica","volume":"37 10","pages":"Pages 2659-2671"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0001-6160(89)90299-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79724795","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: 239

Strain rate continuity in 304 stainless steel during stress rate change tests 应力速率变化试验中304不锈钢的应变速率连续性

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90298-8

D.P. Dunham, J.C. Gibeling

引用次数: 12

Strain path dependence of texture development in aluminum 铝织构发展的应变路径依赖性

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90293-9

T. Takeshita , U.F. Kocks , H.-R. Wenk

引用次数: 10

Creep crack growth and cavitation damage in a 12% CrMoV steel 12% CrMoV钢蠕变裂纹扩展及空化损伤

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90307-6

C. Wiesner, J.C. Earthman, G. Eggeler , B. Ilschner

{"title":"Creep crack growth and cavitation damage in a 12% CrMoV steel","authors":"C. Wiesner, J.C. Earthman, G. Eggeler , B. Ilschner","doi":"10.1016/0001-6160(89)90307-6","DOIUrl":"10.1016/0001-6160(89)90307-6","url":null,"abstract":"<div><p>Creep crack growth of a 12% CrMoV steel has been investigated at 650°C in SENT specimens with and without side-grooves approaching plane strain and plane stress conditions respectively. Experiments have been conducted under different loading conditions including constant <span><math><mtext>C</mtext><msup><mi></mi><mn>∗</mn></msup></math></span>, the <em>J</em>-integral rate parameter. Transitions in crack growth behaviour are observed early in the crack growth and later when the crack becomes long with respect to the specimen width. The early transition is dominated by the initial development of cavitation damage ahead of the crack tip. Once this transition is complete, the correlation between <span><math><mtext>C</mtext><msup><mi></mi><mn>∗</mn></msup></math></span> and the crack growth rate becomes valid. This correlation is independent of loading conditions, it coincides with theoretical expectations and it is valid until the second transition where the extent of damage has a dominant influence on the stress field ahead of the crack tip. A trend has been observed that crack growth is slower in smooth-sided specimens as compared to the crack growth in side-grooved specimens for the same value of <span><math><mtext>C</mtext><msup><mi></mi><mn>∗</mn></msup></math></span>. Metallographic investigations indicate that crack growth occurs by the formation and growth of cavities and microcracks ahead of the crack tip. A comparison of the damage in smooth-sided and side-grooved specimens shows that creep damage is much more extensive under plane stress conditions than under plane strain conditions for the same value of <span><math><mtext>C</mtext><msup><mi></mi><mn>∗</mn></msup></math></span>. This difference is due to the multiaxial stress field, produced by the side-grooves, which influences cavitation and microcrack formation in the material. It also accounts for the smaller crack growth rates in smooth-sided specimens.</p></div>","PeriodicalId":6969,"journal":{"name":"Acta Metallurgica","volume":"37 10","pages":"Pages 2733-2741"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0001-6160(89)90307-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"118938240","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: 14

Effect of preoxidation and grain size on ductility of a boron-doped Ni3Al at elevated temperatures 预氧化和晶粒尺寸对硼掺杂Ni3Al高温塑性的影响

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90301-5

M. Takeyama, C.T. Liu

{"title":"Effect of preoxidation and grain size on ductility of a boron-doped Ni3Al at elevated temperatures","authors":"M. Takeyama, C.T. Liu","doi":"10.1016/0001-6160(89)90301-5","DOIUrl":"https://doi.org/10.1016/0001-6160(89)90301-5","url":null,"abstract":"<div><p>The ductility of a preoxidized Ni<sub>3</sub>Al (Ni-23Al-0.5Hf-0.2B. at.%) alloy with various grain sizes (17–193 μm) was evaluated by means of tensile tests at 600 and 760°C in vacuum. The preoxidation does not affect the ductility of the finest-grained material at either temperature, whereas it causes severe embrittiement in the largest-grained material, especially at 760°C. Auger studies revealed very little oxygen penetration along grain boundaries in the finest-grained material but substantial oxygen penetration in the largest-grained one. A continuous, thin Al-rich oxide layer which forms on the fine-grained samples protects the underlying alloy from oxygen penetration, preventing any loss of ductility, whereas the nickel-rich oxide which forms on the large-grained samples allows oxygen to penetrate along grain boundaries, causing severe embrittiement. The grain boundaries act as short-circuit paths for rapid diffusion of aluminum atoms from the bulk to the surfaces, and this is responsible for the change in oxidation product from Ni-rich to Al-rich oxide with decreasing grain size.</p></div>","PeriodicalId":6969,"journal":{"name":"Acta Metallurgica","volume":"37 10","pages":"Pages 2681-2688"},"PeriodicalIF":0.0,"publicationDate":"1989-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0001-6160(89)90301-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134833173","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: 0

Segregation mechanisms of temper embrittlement 回火脆化的偏析机制

Acta Metallurgica Pub Date : 1989-10-01 DOI: 10.1016/0001-6160(89)90292-7

M. Militzer, J. Wieting

引用次数: 19