于红娇
,
张弓
,
马莒生
稀有金属材料与工程
在gleeblelS00力学试验机上,对Sn-4.5Zn-2Bi-In-P,Sn-9Zn-2.5Bi-In-P,Sn-8Zn-3Bi 3种无铅焊料进行系列恒温恒应变速率的压缩试验,实验系列由3种实验温度(20,60,100℃)和5种应变速率(101,100,10-1,10-2,10-3)正交组成.结果表明:3种无铅焊料的饱和应力随应变速率的增加而增加,随温度的升高而减小;在所有实验系列中,Sn-8Zn-3Bi合金的饱和应力最大,Sn-4.5Zn-2Bi-In-P最小;应用非线性拟合方法分别确定了描述3种无铅焊料非弹性率相关性的Anand粘塑性本构方程的9个材料常数:通过实验数据与Anand模型预测数据的对比分析,表明Anand模型能有效描述3种新型无铅焊料的粘塑性行为,为3种无铅焊料焊点的可靠性模拟和失效分析提供模型支持.
关键词:
新型无铅焊料
,
压缩试验
,
Anand模型参数
段沐枫
,
李宁
,
郑莹莹
,
肖军
,
李勇
宇航材料工艺
K-cor是应用Z-pin增强技术的一种新型高性能结构.本文以NHZP-1树脂为基体研究适合K-cor结构的半固化Z-pin拉挤工艺,得到固化度为51.25％的Z-pin为满足制备要求的最佳参数,并制作悬空装置采用两步法进行半固化Z-pin的植入和压弯,探索出压弯和后固化工艺.在此基础上,对试制的K-cor夹层结构进行平拉和剪切试验研究.结果发现,折弯长度是K-cor夹层结构的另一重要参数,较长的折弯长度会增加Z-pin与蒙皮的结合面积从而提高结构的拉伸性能.
关键词:
复合材料
,
半固化Z-pin
,
K-cor夹层结构
,
制备工艺
,
力学性能
陈篪
金属学报
本文证明我们所建议的关系: (da/dN)-C[(△K)~2-K_2~2/K_1~2-(△K)~2]~p能够很好地表达R=(K_(min)/K_(max))=常数时(da/dN)随△K的全部变化,其中P值在1左右,C约在3×10~(-3)—10~(-2)毫米/周之间。
关键词:
Materials Letters
Single crystals of K-doped blue bronze Rb0.15K0.15MoO3 and Rb0.3MoO3 have been investigated by measurements of the X-ray photoemission spectrum (XPS), electrical resistivity and thermoelectric power, respectively. Analysis of the XPS data reveals that two final states representing alternate screening channels coexist in Rb0.15K0.15MoO3. Compared with the pure bronze, the Mo sites of the doped sample contain less 4d electrons which reflected in the movement of Mo3d spectrum. Due to the discrepancy of electronic structure, the K ion doping results in the notable increase of the single particle activation energy and decrease of the thermoelectric power in the charge density wave state. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
blue bronze;charge-density-wave;electronic structure;nonlinear transport;k0.30moo3;tl0.3moo3;k0.3moo3;moo3
稀土学报(英文版)
Cyclic oxidation test is a fundamental method to assess lifetime of materials in high temperature environment. Cycle length or cyclic frequency is one important variable in cyclic oxidation testing. In present work, cyclic oxidation tests were performed on cast K38 alloys with 0 wt.%, 0.1 wt.%, and 0.5 wt.% yttrium additions at 1 273 K respectively. Two cyclic frequencies were used to investigate the influence of cycle length (1 h vs. 20 h) on the high temperature oxidation behavior of superalloy. The results showed that the degradation of cast K38 alloy critically was dependent on the cyclic frequency. The yttrium addition was beneficial to reducing scale-growth rate, improving the scale adhesion and stress releasing, thereby increased the spallation resistance. It could be drawn that the effect of cyclic frequency was highly dependent on the scale adherence to the substrate.
关键词:
K38 superalloy;yttrium;cyclic oxidation;cyclic frequency;rare earths;high-temperature oxidation;adhesion;segregation;scales;spallation;chromia;alloys;growth;oxides
Physics Letters A
Except for a Peierls transition at T(p) = 180 K, a new transition around T = 270 K in K0.3MoO3 single crystals has been found as evidenced by the anomalies in electrical, magnetic and thermodynamic properties. This transition may be caused by the variation of carrier characteristics or of the charge transfer between cations and anions.
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