WANG Shuhe
,
DAI Tongfu
,
SHI Changxu
材料科学技术（英文）
The effect of La element on the mechanical properties and constitution nearby grain boundary in a Co-base superalloy Co-22Ni-22Cr-14k during 760℃ ageing has been investigated by AES and material testing. Results show that element La can be in a state of solid solution and segregates mainly at the vicinity of grain boundaries. The prior segregation of La atoms can affect segregation behaviour of other elements, so that exerts influence on microstructure of the alloy, Particularly increasing of La content can decrease P concentration at the vicinity of grain boundaries but not decrease S concentration. S together with La produce cosegregation effect. The content of La has no obvious effect on high temperature strength. When the content of La comes up to 0.02wt-%, it can obviously improve the high temperature ductility.
关键词:
La
,
null
,
null
Journal of Materials Research
Based on the best bulk metallic glass (BMG) forming alloy in the Mg-Cu-Y ternary system, we introduced Ag (or Ni) to partially substitute for Cu to improve the glass-forming ability (GFA). The objective of this paper is twofold. First, we illustrate in detail a recently developed search strategy, which was proposed but only briefly outlined in our previous publication [H. Ma, L.L. Shi, J. Xu, Y. Li, and E. Ma: Discovering inch-diameter metallic glasses in three-dimensional composition space. Appl. Phys. Lett. 87, 181915 (2005)]. The protocol to navigate in three-dimensional composition space to land large BMGs is spelled out step-by-step using the pseudo-ternary Mg-(Cu,Ag)-Y as the model system. Second, our ability to locate the best BMG former in the composition tetrahedron allows us to systematically examine, and conclude on, the effects of a given alloying element. The large improvement in glass-forming ability in the Mg-(Cu,Ag)-Y system relative to the based ternary will be contrasted with the reduced glass-forming ability in the Mg-(Cu,Ni)-Y pseudo ternary system. It is demonstrated that the improvement of glass-forming ability requires judicious choice of substitutional alloying elements and concentrations, rather than simple additions of multiple elements assuming the "confusion principle."
关键词:
bulk metallic-glass;shaped copper mold;amorphous-alloys;thermal-stability;ternary-system;casting method;p system;diameter;zr;mm
孙保基
,
张葆
,
宋策
,
龙思源
液晶与显示
doi:10.3788/YJYXS20163109.0921
针对TLD算法的特征点无法有效表述目标问题，提出了一种基于角点增强改进的TLD目标跟踪算法。改进算法在跟踪模块加入了对目标表述能力更强，具有光照不敏感性和旋转不变性的 Shi-Tomas 角点作为跟踪特征点。跟踪器运行时，在角点经光流法跟踪和双向误差检测后，利用剩余的稳定角点定位目标窗口。对照结果表明，改进算法在面对目标抖动和形变时可以稳定跟踪；有效抑制因跟踪平滑点造成的漂移现象；提高了跟踪的稳定性。针对 TLD算法跟踪过程中因在线模板积累造成的计算量持续增大、实时性持续降低的问题，提出了一种依据相似度中值的模板判断删除机制。该删除机制在模板积累到设定阈值时运行，根据模板与当前目标的相似度，删除不再具备代表性的模板；调整模板空间并更新模板数目。实验表明，该删除机制在应对模板更新快、持续时间长的跟踪情景时有效降低算法计算量，实时性可提高约20％。
关键词:
目标跟踪
,
TLD
,
角点特征
,
在线模板
