全文获取类型
收费全文 | 304篇 |
免费 | 12篇 |
国内免费 | 23篇 |
专业分类
综合类 | 12篇 |
化学工业 | 2篇 |
金属工艺 | 169篇 |
机械仪表 | 19篇 |
建筑科学 | 1篇 |
矿业工程 | 5篇 |
能源动力 | 9篇 |
石油天然气 | 1篇 |
武器工业 | 5篇 |
一般工业技术 | 96篇 |
冶金工业 | 17篇 |
原子能技术 | 1篇 |
自动化技术 | 2篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 25篇 |
2012年 | 13篇 |
2011年 | 39篇 |
2010年 | 20篇 |
2009年 | 34篇 |
2008年 | 25篇 |
2007年 | 28篇 |
2006年 | 27篇 |
2005年 | 20篇 |
2004年 | 14篇 |
2003年 | 4篇 |
2002年 | 3篇 |
排序方式: 共有339条查询结果,搜索用时 15 毫秒
91.
AbstractA nanograin sized model oxide dispersion strengthened (ODS) ferritic steel with nominal composition Fe–14Cr–0·3Y2O3 (wt-%) was produced by mechanical alloying and consolidated by hot isostatic pressing. The alloy was submitted to severe plastic deformation by equal channel angular pressing (ECAP). Microstructural and mechanical characterisation was performed before and after ECAP. It was found that ECAP decreases and homogenises grain size without altering the nanoparticle dispersion, in addition to enhancing ductility and shifting the strength drop at high temperatures. 相似文献
92.
Microstructure and mechanical properties of AZ31-0.5%Si(mass fraction) alloy processed by ECAP were investigated. Results show that Mg2Si phase formed during solidification can be broken up and be dispersed in matrix by ECAP. With the increase of ECAP passes, Mg2Si phase in microstructure tends to distribute uniformly. The mean grain size is about 4 μm, and the mean size of Mg2Si is about 6 μm. The elongation of AZ31-0.5%Si alloy is significantly increased after ECAP and then changes a little with increasing ECAP passes, The ultimate strength of as-extruded AZ31-0.5%Si alloy reaches 348.9 MPa, while its strength decreases after ECAP. 相似文献
93.
等通道转角挤压(ECAP)是使材料发生剧烈塑性变形的一种加工方法。综述了ECAP工艺制备超细晶材料的组织及性能的研究进展。分析了超细晶材料的组织影响因素及特征,并对力学特性、热稳定性、疲劳性能、耐腐蚀性和磁性能进行了重点探讨。随着研究的深入,ECAP工艺将具有更广阔的工业化应用前景。 相似文献
94.
Faramarz Djavanroodi Ali Asghar Zolfaghari Mahmoud Ebrahimi Kamran Nikbin 《金属学报(英文版)》2014,(1):95-100
A new technique to produce ultra-fine grained tubular specimen has been proposed,and the experiments have been performed using equal channel angular pressing(ECAP) with an angle of 90° between two intersecting channels and also the use of rubber pad as a mandrel during process.Commercial purity copper tubes have been pressed up to three passes through four different fundamental routes(A,B_A,B_C,and C) directions of which are identified in the text below.The influence of each route on the value,distribution,and homogeneity of hardness has been investigated by applying Vickers micro-hardness measurements at various locations of the tube's transverse planes.Significant enhancement of the hardness is observed after the first pass ECAP.Also,routes C and B_C show,respectively,better average hardness magnitude and hardness distribution uniformity.In addition,the results indicate that there is about 50%and 62%reduction of the grain size,compared to the annealed condition,following ECAP process of the copper tube sample after the first and the third pass via route B_C. 相似文献
95.
等通道挤压Mg2Si增强ZK60镁合金的显微组织及力学性能 总被引:1,自引:0,他引:1
研究等通道挤压(ECAP)对ZK60+2Si镁合金显微组织、室温力学性能和高温抗蠕变性能的影响。结果表明,合金铸态组织主要由-Mg基体、Mg2Si相和MgZn相组成,等通道挤压可显著碎化原粗大汉字状Mg2Si相并使其趋于弥散分布,同时基体组织也得到细化。挤压4道次后,合金的室温抗拉强度由154.8MPa增加到270MPa,伸长率由4.5%增加到17.5%。挤压6道次后,合金的伸长率进一步增加到21%,而抗拉强度却下降至261MPa;合金的高温蠕变寿命由铸态20h延长到203h,稳态蠕变速率下降了约1个数量级,这主要是因为细小颗粒状MgSi相有效阻止了晶界滑移。 相似文献
96.
Three high-purity Nb single crystals with different orientations are deformed by equal-channel angular pressing (ECAP) at room temperature for one pass. The microstructures of two different cross-sections are systematically characterized by means of electron backscatter diffraction on various length scales. The completely different microstructural features of the three single crystals provide clear experimental evidence that crystallographic orientation has a strong influence on orientation splitting and on microstructural heterogeneity. Lattice rotation is analyzed by comparing the crystal orientation before and after ECAP. The orientation evolution reveals that the three crystals tend to align in such a way that the primary slip plane and the primary slip direction overlap with the simple shear plane and direction, respectively. An in-depth analysis of the large misorientation bands is given in a companion paper. 相似文献
97.
研究近α钛合金TA15经等通道转角挤压工艺(ECAP)加工后的维氏显微硬度及其变化规律。结果表明:TA15合金经ECAP挤压后,显微硬度显著提高,且合金试样外层硬度略高于芯部。合金的显微硬度与组织畸变程度、位错密度、晶粒尺寸以及相组成等密切相关。相变点以下挤压,挤压温度越低,硬度越高;相变点以上挤压,由于挤压后水冷过程中在β相内产生针状马氏体α′,硬度明显高于相变点以下挤压。模具转角越小,显微硬度越高。随挤压次数增加,硬度先增大后保持基本不变,而挤压路径对硬度的影响与挤压次数、挤压后细化效果密切相关。TA15合金经ECAP后退火,显微硬度明显降低。 相似文献
98.
等径角挤压处理后的Mg-Gd-Y-Zr合金的微观组织和力学性能 总被引:1,自引:0,他引:1
研究等径角挤压过程中材料的微观组织和织构演变以及对其力学性能的影响。结果表明:挤压4道次后的微观组织是不均匀的,即在此过程中形成了粗晶区和细晶区2个区域。颗粒诱发的再结晶机制导致晶粒细化,在4道次后形成了更加随机的织构。与挤压前的原始材料相比较,经等径角挤压处理的材料虽然强度没有增加,但是塑性有了显著的提高。用织构改变和第二相颗粒解释了合金塑性的变化。 相似文献
99.
室温下,对923 及1023 K退火1 h所得的不同原始晶粒尺寸的工业纯钛进行ECAP变形。通过TEM、EBSD、室温拉伸和显微硬度测试研究原始晶粒尺寸对ECAP变形纯钛组织性能的影响。探讨纯钛ECAP变形孪生行为和变形机制。结果表明,退火温度越高,原始晶粒尺寸越大。1道次变形后,1023 K退火纯钛的晶粒细化效果更显著。4道次变形后,923 K退火纯钛的组织更细小均匀。随着变形道次的增加,屈服强度不断增大,1道次变形后增幅最大,约为100%,且原始晶粒尺寸越大,强度增幅越大。纯钛ECAP变形机制包括位错滑移和孪生,原始晶粒尺寸越大,孪晶数量越多。 相似文献
100.