Ying Yan
,
Wan-Peng Deng
,
Zhan-Feng Gao
,
Jing Zhu
,
Zhong-Jun Wang
,
Xiao-Wu Li
金属学报(英文版)
doi:10.1007/s40195-016-0373-6
To explore the coupled effect of temperature T and strain rate ε˙ε˙ on the deformation features of AZ31 Mg alloy, mechanical behaviors and microstructural evolutions as well as surface deformation and damage features were systematically examined under uniaxial tension at T spanning from 298 to 523 K and ε˙ε˙ from 10-4 to 10-2 s-1. The increase in T or the decrease in ε˙ε˙ leads to the marked decrease in flow stress, the appearance of a stress quasi-plateau after an initially rapid strain hardening, and even to the occurrence of successive strain softening. Correspondingly, the plastic deformation modes of AZ31 Mg alloy transform from the predominant twinning and a limited amount of dislocation slip into the enhanced non-basal slip and the dynamic recrystallization (DRX) together with the weakened twinning. Meanwhile, the cracking modes also change from along grain boundaries (GBs) and at twin boundaries (TBs) or the end of twins into nearby GBs where the DRX has occurred. The appearance of a stress quasi-plateau, the formation of large-sized cracks nearby GBs, and the occurrence of continuous strain softening, are intimately related to the enhancement of the non-basal slip and the DRX.
关键词:
AZ31
,
Mg
,
alloy
,
Uniaxial
,
tension
,
Temperature
,
Strain
,
rate
,
Deformation
,
Damage
,
Twinning
Zhenyu YUAN
材料科学技术（英）
The superelastic properties of NiTi thin films prepared with sputtering were studied. To characterize their superelasticity, tensile and bulging and indentation tests were performed. The measured mechanisms using these three methods were compared, and the factors that influence superelasticity were described.
关键词:
Shape memory alloy
,
memory
,
alloy
,
NiTi
,
thin
,
film
,
Super
Jun ZHANG
材料科学技术（英）
An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.
关键词:
Cathodic arc ion plating
,
arc
,
ion
,
plating
,
alloy
,
coating
,
a
李美栓
,
钱余海
,
辛丽
腐蚀科学与防护技术
氧化物与形成该氧化物消耗的金属的体积比（Ｐｉｌｌｉｎｇ－Ｂｅｄｗｏｒｔｈ Ｒａｔｉｏ简称ＰＢＲ）是判断氧化膜完整性的一个重要判据，也是氧化膜内产生生长应力的主要因素之一，已发发表的关于ＰＢＲ的数据都是针对纯金属的，本文基于合金的氧化行为建立了一个简化的模型，给出了合金上形成的氧化物的ＰＢＲ的人体估算了Ａｌ２Ｏ３、ＮｉＯ及Ｃｒ２Ｏ３等几种氧化物膜以及它们的混合膜ＰＢＲ值，合金上氧化物的ＰＢＲ值与合金 成分有关,并与纯金属上形成的同种氧化物的PBR有显著差别.
关键词:
氧化
,
oxide scale
,
alloy
,
null
,
null
王德宁
,
王渭源
金属学报
本文应用金属中Wigner-Sietz(W-S)半径数据和引入等效电荷概念,结合Ziegler的质子注入数据,导出了计算重离子注入各种金属中的电子阻止本领S_c(E)的公式,计算结果与文献中的实测值结果甚为一致。同样,应用合金中的W-S半径,导出了适用于合金硼化物和CsCl型合金的S_c(E)计算公式。计算结果表明,公式对单硼或二硼化合物符合得较好,而对一些复杂结构的合金以及Cr_5B_3和W_2B_5是不适合的。对CsCl型合金,S_c(E)对Bragg定律的偏离系数γ和合金中电荷转移量成正比,后者越大表明金属键越强,则合金对离子的阻止本领越大,这与实验结果是吻合的。合金中两元素在同一周期中位置相差越远,这种趋势越明显。不同周期元素组成的合金更加强了这种趋势。
关键词:
金属
,
alloy
,
range parameter
,
stopping power
廖彬
,
雷永泉
,
吕光烈
,
陈立新
,
葛红卫
,
潘洪革
金属学报
XRD Rietveld分析显示, LaxMg3-xNi9(x=1.0-2.3)均由六方PuNi3型结构的主相及少量LaNi5及MgNi2杂相组成,主相的晶胞参数随x的增加而线性增大。合金的氢化物仍保持PuNi3型结构, 但其晶胞体积有较大的膨胀。电化学测试表明, 随x增加, 合金的最大放电容量由88.3 (x=1.0)逐渐增大到397.5 mAh/g(x=2.0)， 然后又降低到230 mAh/g(x=2.3)。对放电容量超过348 mAh/g的合金(x =1.7-2.2), 在放电电流i=400-1200 mA/g的条件下, 合金的高倍率放电性能(HRD)均随x增加而有不同程度的降低.HRD的缓慢降低主要与合金电极进行电荷迁移反应时的电催化活性的逐渐降低有关, 而在x>2.0时, HRD的快速降低与氢在合金中的扩散速率明显降低有关.上述合金经100次循环后合金的容量保持率为55.7%-62.9%，容量衰退较快与循环过程中La和Mg的氧化腐蚀以及合金较大的吸氢体积膨胀率有关。
关键词:
La-Mg-Ni型贮氢合金
,
hydrogen storage
,
alloy
Journal of Applied Physics
The effect of the atomic disorder-order transformation on remanence enhancement and coercivity in isotropic CoPt magnets has been studied by isothermal annealing at 675 degreesC, well below the transformation temperature, for 10-80 min after quenching from 900 degreesC. The results of x-ray diffraction, alternating-current susceptibility, and magnetization measurements indicate that the strong remanence enhancement effect originates from exchange coupling between the face-centered-tetragonal ordered hard-magnetic precipitated phase and the face-centered-cubic disordered soft-magnetic matrix phase during the initial ordering transformation. The nonuniform distribution of the magnetic anisotropy results in a lower reversibility, unlike the so-called exchange spring magnet. (C) 2002 American Institute of Physics.
关键词:
alloy
Ruihua HU
,
Montasser M.Dewidar
,
Hyo-Jin KIM
,
Jae-Kyoo LIM
,
null
材料科学技术（英）
In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study, titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase, respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer (EPMA) and X-ray diffraction (XRD) method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.
关键词:
Ti-6Al-4V
,
alloy
,
Wear
,
Sintering
,
reaction
