Zesheng JI
,
Maoliang HU
,
Xiaoping ZHENG
材料科学技术（英）
To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results show that critical forming forces and maximal forming forces could be obtained and related to the holding times in the semi-solid forming process. In the holding time of 0-2700 s, with increasing the holding time, maximal forming force decreased sharply and critical forming force decreased slowly. In the whole thixotropic flowing process, the filling-in was steady and the surface fineness was good. The forming force increased when the slurry changed the flowing direction or flowed from the big-diameter chamber to the small-diameter one. The tensile strength and elongation to failure of the sample after holding time for 2700 s, compared to as-cast sample, are increased by approximately 42.7% and 180%, respectively, and the fractured surfaces presented dimple-like pattern.
关键词:
AZ91D magnesium alloy
,
magnesium
,
alloy
,
semi-solid
,
thixot
中国腐蚀与防护学报
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关键词:
Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms
A static Monte Carlo simulation program has been used to study the influence of primary and secondary knock-on atoms on the angular distribution and the fractionation, for zero-fluence sputtering of Mo-92-Mo-100. At 10 keV Xe ion energy, calculations show that significant depth-dependent momentum asymmetry exists in the near-surface region, as in Refs. (L.P. Zheng, R.S. Li, M.Y.LI, Nucl. Instr, and Meth. B 100 (1995) 490; L.P. Zheng, M.Y. Li, Nucl. Instr. and Meth. B 114(1996) 28). The calculations also show that at the polar emission angle range between 0 degrees and 90 degrees the probabilities of the sputtered primary knock-on atoms for Mo-92 and Mo-100 are small (6.1% for Mo-92 and 6.6% for Mo-100), especially, between 0 degrees and 30 degrees they are very small (2.5% for Mo-92 and 2.8% for Mo-100). At 0.1 keV Ar ion energy, the calculations show that partial momentum flux ratios, for the primary and the secondary knock-on atoms, deviate far from one, through marker plane 1 (about an atomic layer distance from the surface). (C) 1998 Elsevier Science B.V. All rights reserved.
关键词:
mo-92-mo-100;targets
李红
,
孙克
,
李艳萍
,
石毅
,
郭金花
,
卢志超
金属功能材料
提出了采用推杆式热膨胀仪测试非晶合金薄带热膨胀特性的新方法.分析了Fe80Si9B11非晶薄带的热膨胀曲特性和非晶合金晶化过程.根据R.G.Zheng理论分析了结构弛豫中自由体积比变化,发现自由体积比曲线出现双峰.结合晶化前发生相分离的理论分析了这种变化的原因.分析表明:铁基非晶Fe80Si9B11晶化过程中先形成α-Fe(Si)相,再析出Fe3B、二次α-Fe(Si)相.晶化前先发生相分离,自由体积比增大,然后析出结晶相α-Fe(Si),自由体积比降低.随温度升高,B偏聚,自由体积比增大,随后析出Fe3B、二次α-Fe(Si)相,自由体积比降低.
关键词:
铁基非晶薄带
,
热膨胀系数
,
自由体积比
,
结构弛豫
