首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1068篇
  免费   99篇
  国内免费   135篇
电工技术   4篇
综合类   30篇
化学工业   39篇
金属工艺   738篇
机械仪表   60篇
建筑科学   1篇
矿业工程   11篇
能源动力   5篇
武器工业   9篇
无线电   26篇
一般工业技术   239篇
冶金工业   99篇
原子能技术   2篇
自动化技术   39篇
  2024年   3篇
  2023年   20篇
  2022年   31篇
  2021年   58篇
  2020年   65篇
  2019年   77篇
  2018年   44篇
  2017年   56篇
  2016年   37篇
  2015年   28篇
  2014年   42篇
  2013年   52篇
  2012年   67篇
  2011年   70篇
  2010年   55篇
  2009年   80篇
  2008年   65篇
  2007年   70篇
  2006年   85篇
  2005年   62篇
  2004年   43篇
  2003年   23篇
  2002年   18篇
  2001年   18篇
  2000年   17篇
  1999年   17篇
  1998年   8篇
  1997年   18篇
  1996年   19篇
  1995年   13篇
  1994年   9篇
  1993年   4篇
  1992年   11篇
  1991年   1篇
  1990年   4篇
  1989年   7篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
排序方式: 共有1302条查询结果,搜索用时 15 毫秒
1.
黄均毅  杨扬 《矿冶工程》2022,42(5):143-147
使用分离式霍普金森压杆对选区电子束熔炼的Ti-6Al-4V合金棒材进行动态加载,通过动态加载曲线对比、X射线衍射及金相观察,分析了晶界和hcp-α相取向对纵/径向试样绝热剪切行为的影响。结果表明,纵向试样的临界应变和绝热剪切形成能均比径向试样的小,即绝热剪切敏感性比径向试样的高,因此试样在纵/径方向上存在绝热剪切各向异性。在同一加载方向下,晶界与hcp-α相取向对材料流变应力的影响相反,而且hcp-α相取向的作用更强。当hcp-α相的c轴平行于加载方向时(纵向试样),材料的流变应力更大、变形做功更多、热软化效应更强,因此纵向试样更易发生绝热剪切。  相似文献   
2.
《Ceramics International》2022,48(17):24346-24354
The borided layer was prepared on the surface of the Ti–5Mo–5V–8Cr–3Al alloy by powder-pack boriding at 1000°C-10h. SEM, EPMA and TEM were used to investigate the effects of alloying elements (Al, V, Mo and Cr) on the growth of TiB whiskers in the borided Ti–5Mo–5V–8Cr–3Al alloy. Wear properties of borided Ti–5Mo–5V–8Cr–3Al alloy were investigated using dry reciprocating friction tests. SEM results show that the thickness of boride layer in Ti–5Mo–5V–8Cr–3Al alloy is thinner than that in the Cp-Ti. This is attributed to the enrichment of alloying elements especially V in TiB/substrate by TEM, which hinders the diffusion of B atoms, thus resulting in the short and thick TiB whiskers in Ti–5Mo–5V–8Cr–3Al alloy. Borided Ti–5Mo–5V–8Cr–3Al alloy has the better wear resistance than as-received alloy.  相似文献   
3.
Thermal compression testing was investigated using the Gleeble 3800 thermal simulator,and thermal deformation behavior of particle-reinforced titanium matrix composites (TMCs) was studied under deformation temperatures of 750-900 ℃,strain rates of 0.001-1 s-1,and experimental deformation of 60%.According to obtained flow stress curves,the hot deformation characteristics were analyzed.Based on the Arrhenius hyperbolic sinusoidal model,the constitutive equation at high tempera-ture was established.Based on the theory of dynamic material models,a hot processing map of TMCs at high temperature was established,and the peak region of power dissipation rate and the instability region in the hot processing map were both determined.At the same time,the corresponding microstructures in the peak power dissipation rate and rheological instability regions were observed.The results showed that flow stress decreased with increasing deformation temperature and increased with increasing strain rate.The thermal deformation activation energy of titanium matrix composites was 301.8 kJ/mol.The Ti-6Al-4V/(TiB + TiC) composites possessed only one instability zone under high-temperature compression at a strain of 0.5,with corresponding temperatures at 750-840 ℃ and strain rates at 0.1-1 s-1.The optimal thermal deformation parameters included corresponding temperatures of 830-880 ℃ and strain rates of 0.001-0.05 s-1.The microstructures corresponding to optimal hot working parameters in processing maps were more homogeneous than the microstructures in the instability zone,including the distribution uniformity of reinforcement and the degree of dynamic recrystallization,and no instability phenomena including abnormal grain growth,microcracks or intensive fracture of reinforcements were found,indicating that the hot processing map had a positive guiding effect on the option of desirable material thermal-working parameters.  相似文献   
4.
本文研究了SiC和Al2O3颗粒对生物医用植入材料Ti-25Nb-3Mo-3Zr-2Sn合金的微磨损行为的影响。在文中研究了合金的比磨损率、摩擦系数、磨损机制以及微磨损与腐蚀之间的协同作用。研究结果显示,合金的比磨损率随磨粒尺寸的增加而增加。由于SiC磨粒的硬度和切削性均优于Al2O3磨粒,由此在同尺寸磨粒下SiC磨粒所造成的材料的损失比Al2O3磨粒造成的要大。摩擦系数的结果显示,在同一种磨粒作用下,Hank’s溶液中所获得的摩擦系数的平均值大于蒸馏水中所获得的摩擦系数平均值,且由于Hank’s溶液的腐蚀性所致在Hank’s溶液中获得的摩擦系数的稳定性要比在蒸馏水中的稳定性差;在同尺寸磨粒下,Al2O3磨粒所造成的摩擦系数要大于SiC磨粒所造成的。随磨粒尺寸的减小,磨损机制由三体磨损转变为混合磨损之后再转变为二体磨损。从磨损机制图中可以看出腐蚀对材料损失的贡献是不容小视的,磨损机制为以磨损为主的磨损腐蚀。  相似文献   
5.
Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation. In the current study, the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm. A three-dimensional finite element model is established to simulate the temperature distribution of laser welding process. The thermal cycle curves are produced on the strength of the simulation results. Meanwhile, the microstructure characteristics of the welded joint are investigated combined with simulation results. The results show that weld zone, heat affected zone and based metal experience similar thermal cycles process and the cooling rate has an important influence on the formation of microstructure. Moreover, the simulation results are well matched with experiment results.  相似文献   
6.
The different types of metal powder used for selective laser melting(SLM) process would cause distinct corrosion behavior due to the uniformity of the obtained microstructure.The SLM-produced Ti–5Cu alloy using atomized Ti–5Cu metal powder(SLMed Ti–5Cu) in this work reveals a relatively uniform microstructure with overwhelming acicular α/α′ phase and shows great advantages on corrosion resistance compared with the SLM-produced Ti–5Cu alloy using the mixture powder(SLMedM Ti–5Cu).The effect of the micro-galvanic cells decreases due to the undetectable Ti_2Cu phase in the microstructure of the SLMed Ti–5Cu.An apparent passivation behavior was observed for SLMed Ti–5Cu instead of severe pitting phenomenon for the SLMed-M Ti–5Cu.The charge transfer resistance of SLMed Ti–5Cu in this work is 10.09 ± 2.63 MΩ cm~2, which is significantly higher than that of SLMed-M Ti–5Cu(4.76 MΩ cm~2).The above result indicates the atomized Ti–5Cu powder plays an important role in the formation of the uniform microstructure of SLMed product, thereby enhancing its corrosion resistance in Hank's solution at 37 ℃.  相似文献   
7.
本研究分别利用水冷铜坩埚真空感应熔炼气雾化(VIGA-CC)和等离子旋转电极(PREP)两种技术制备出球形Ti-6Al-4V合金粉末,作者利用SEM、同步辐射CT扫描-三维重建和氩气含量测试等分析手段对不同粒径的Ti-6Al-4V合金粉末的孔洞缺陷和氩气含量、硬度值进行了表征。实验结果表明, VIGA-CC粉末粒度分布宽,细粉收得率较多,粉末粒度分布在40~180 μm之间, PREP粉末的粒度分布较窄,主要集中在110~180 μm之间;金属粉末内部的孔隙率、气体含量和孔尺寸随着粉末粒度的增大而增大,且同一粒径范围内VIGA-CC粉末的气孔概率多于PREP粉末;随着粉末粒径减小,粉末截面组织逐渐细化,其硬度值逐渐升高,整体上VIGA-CC粉末硬度值高于PREP粉末。  相似文献   
8.
本文主要研究分段电压对于钛合金表面所制备的微弧氧化膜层特性的影响。利用扫描电子显微镜(SEM)和激光扫描共聚焦显微镜对MAO膜层的结构进行了表征,利用能谱分析(EDS)和X射线衍射(XRD)并对膜层成分进行分析。对比评价了不同分段电压模式下膜层的厚度、粗糙度和耐蚀性。结果表明,与不同分段电压相比,第一阶段电压为320V 氧化时间180s与第二阶段电压为420V氧化时间为720s,所形成的膜层粗糙度最小。第一阶段外加电压320V氧化时间120s与第二阶段外加电压420V时间780s,膜层最为致密,耐腐蚀性最好。XRD结果表明,膜层是由TiO2和亚稳态Ti2O3组成。  相似文献   
9.
采用Ti-50Ni(at%)钎料实现了TZM合金与ZrC_p-W复合材料的真空钎焊连接,通过SEM、EDS、XRD等方法分析了接头界面的微观组织结构,研究了钎焊温度对TZM/Ti-50Ni/ZrC_p-W接头界面组织及性能的影响。结果表明:钎焊接头的典型界面结构为TZM/Ti-Mo+TiNi_3+Mo-Ti-W/Ti Ni+TiNi_3+W(s,s)+(Ti,Zr)C/ZrC_p-W。随着钎焊温度的升高,Ti-Mo固溶体层宽度逐渐增大,线状条纹增多、增宽,组织逐渐粗大,晶界变圆滑;接头的抗剪强度随钎焊温度升高先升高后降低,当钎焊温度为1340℃,保温10 min时,接头获得最大抗剪强度为146 MPa。  相似文献   
10.
The microstructural evolution and precipitation location of the secondary phase of an as-cast Ti-25V-15Cr-0.3Si titanium alloy were investigated via isothermal compression experiments and heat treatment. The average aspect (length-to-width) ratio, average area and size of the grains at different heat treatment temperatures and holding time were analyzed and the effects of deformation and annealing time on the grain area and size were considered. It was found that the grain size was strongly influenced by the height reduction and holding time. Grain growth was significant when annealing time increased from 10 min to 2 h at 950 °C and height reduction of 30%; however, grain growth was minimal at annealing time between 2 and 4 h. Many dispersion particles were observed to form in continuous chains; the precipitation location was confirmed to be along initial grain boundaries, and the dispersion particles were identified to be Ti5Si3 phase by TEM.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号