LUO Fang
,
YAO Jianhua
,
HU Xiaxia
,
CHAI Guozhong
钢铁研究学报(英文版)
Abstract: In this paper, H13 powder is cladded on P20 base during continuous CO2 laser, the influence of processing technologies such as the laser power is analyzed. The 3-D model of synchronous powder feeding is established under Gauss heat source, the simulation results are compared with the experimental data. The results show that the temperature field and the size of heat affected zone are affected by laser power. In the heat affected zone, experimental sizes are compared with simulative sizes, the average errors in width and in depth are 15% and 4.5%, respectively.
关键词:
ZHANG Qunli
,
YAO Jianhua
,
Jyoti Mazumder
钢铁研究学报(英文版)
Multilayer of laser direct metal deposition (DMD) was prepared by depositing a gas atomized prealloyed powder with a composition close to Inconel 718 alloy on Inconel 718 high temperature alloy substrate. The effects of the DMD parameters on the buildup rate and the structure of the deposited layer were studied. The laser DMD sample was further processed by a solution treatment. The microstructure and property of the laser DMD zone before and after heat treatment were investigated as well. The results show that the laser parameters of actual laser power of 650 W, scanning speed of 58 mm/s, beam diameter of 1 mm, powder feed rate of 645 g/min, with a corresponding specific energy of 90-130 J/mm2, can be recommended as optimum parameters for high buildup rate of Inconel 718 alloy. Under the condition of optimized parameters, a directional solidification microstructure was obtained and the average distance between the columnar crystals was 5-10 μm. The microcomposition segregation was found between the columnar crystal trunk and columnar crystal. The elements of Nb, Mo, Ti concentrated in the columnar crystal trunk. After the heat treatment, the segregation was greatly minimized, and the segregation ratios were close to 1. The hardness of the laser deposited layer did not show obvious difference along the height of the layer either for the asdeposited layer or for the heat treated layer. However, the microhardness of the laser DMD zone after heat treatment was obviously higher than that after the asdeposited treatment. During the heat treatment process, some Nb and Morich phases precipitated and strengthened DMD layer.
关键词:
laser DMD; Inconel 718 alloy; composition segregation; microstructure; hardness
Applied Physics a-Materials Science & Processing
Amorphous aluminate YAlO3 (YAO) thin films on n-type silicon wafers as gate dielectric layers of metal - oxide semiconductor devices are prepared by pulsed laser deposition. As a comparison, amorphous aluminate LaAlO3 (LAO) thin films are also prepared. The structural and electrical characterization shows that the as-prepared YAO films remain amorphous until 900 degrees C and the dielectric constant is similar to 14. The measured leakage current of less than 10(-3) A/cm(2) at a bias of V-G = 1.0 V for similar to 40-nm-thick YAO and LAO films obeys the Fowler Nordheim tunneling mechanism. It is revealed that the electrical property can be significantly affected by the oxygen pressure during deposition and post rapid thermal annealing, which may change the fixed negative charge density at the gate interface.
关键词:
hafnium oxide;si;stability;silicon;transition;dioxide;devices;hfo2
李玉伟
,
陈继红
,
唐东明
,
张豹山
,
鹿牧
,
陆怀先
功能材料与器件学报
doi:10.3969/j.issn.1007-4252.2010.02.011
制备了一系列具有铁磁/反铁磁交换偏置作用的[NiO/Fe65Co35]10多层膜,使用振动样品磁强计(VSM)测量了样品的静磁参数,利用微带线法测量了样品4GHz-10GHz的磁谱,首次制备并测得了自然共振频率(fr)在6GHz以上,最高到f=9.6GHz的薄膜样品.结果表明交换偏置场(Hex)、各向异性场(Hua)、以及矫顽力(Hc)随铁磁层厚度(tFM)增大而减小;基于Landau-Lifishitz (L-L)方程对静磁参量和磁谱进行了比较,发现样品自然共振频率较L-L方程计算值偏大30%以上.
关键词:
铁磁
,
反铁磁
,
交换偏置场
,
各向异性场
,
交换耦合能密度
,
自然共振频率
徐菊良
,
邓博
,
孙涛
,
李劲
,
蒋益明
金属学报
doi:10.3724/SP.J.1037.2009.00598
利用Thermo-Calc软件并结合金相显微镜,定性研究了2205双相不锈钢在800℃下敏化不同时间后的微观组织演变过程.通过研究扫描速率、介质成分、介质温度和试样表面状态优化了双环电化学动电位再活化法(DL-EPR),并用该优化方法研究了2205双相不锈钢晶间腐蚀敏感性.结果表明:DL-EPR法能定量评价σ相对2205双相不锈钢晶间腐蚀敏感性的影响,随敏化时间延长,σ相含量增多,晶jian 腐蚀敏感性也随之增加.腐蚀形貌的观测验证了这一规律,
关键词:
2205双相不锈钢
,
DL-EPR
,
晶间腐蚀敏感性
,
σ相
