共查询到18条相似文献,搜索用时 178 毫秒
1.
根据弹性理论和多晶膜的屈服强度公式,计算了附着在基体上体心立方多晶薄膜中不同取向晶粒中的应变能密度.结果表明:1)在屈服之前,对Fe和Ta两种薄膜,4个最小的应变能密度对应的晶粒取向依次为(100),(510),(410)和(511);对Cr,Mo,Nb和V四种薄膜,4个最小的应变能密度对应的晶粒取向依次为(111),(332),(322)和(221);对W膜,应变能密度与晶粒取向无关.2)在屈服的体心立方多晶膜中,4个最小的应变能密度对应的晶粒取向依次为(100),(111),(110)和(411).从
关键词:
体心立方多晶薄膜
晶粒取向
应变能密度
织构 相似文献
2.
利用已有的α和β石英压缩性、热膨胀性、弹性及相变温度压力资料,计算了α-β石英相转变时,α和β石英的晶胞参数。依据虎克定律以及高压下β石英的弹性参数,估算了α-β石英相转变时的应变、应力和应变能。结果表明,在0~1.1 GPa条件下,随压力升高,α-β石英相变的线应变介于-0.006~0.005之间,体应变介于-0.016~0.012之间,应力介于-0.46~0.14 GPa之间;应变能介于965~2 760 kJ/m3之间。压力为0.5 GPa左右时,α-β石英相变的应变、应力和应变能均达到最小值。在此基础上,讨论了壳内大规模酸性岩浆活动引起的α-β石英相变对壳内岩石的作用。 相似文献
3.
《高压物理学报》2021,35(3)
为研究软质高分子聚合物材料的静、动态拉伸力学性能,利用Instron-5943万能材料试验机和改进型分离式霍普金森拉杆(SHTB)实验装置对聚氯乙烯(PVC)弹性体材料进行了静、动态拉伸实验,得到了该材料在应变率为0.1 s~(-1)及400~1 850 s~(-1)下的应力-应变曲线。动态拉伸实验过程中,联合波形图分析和高速摄像方法对试样连接方式和胶黏剂进行了优选,通过脉冲整形器延缓入射波上升沿以实现恒应变率加载,调整入射杆与吸收杆间空隙解决了入射波基线偏离问题。结果表明:PVC弹性体在准静态(0.1 s~(-1))拉伸载荷下具有明显的线弹性特征,在动态(400~1 850 s~(-1))拉伸载荷下具有一定的黏性特征。构建了朱-王-唐(ZWT)非线性黏弹性本构模型以表征PVC弹性体材料的黏弹性力学特征,实验与模型拟合结果较吻合。 相似文献
4.
5.
采用LMTO能带方法,对两种不同应变状态下(自由形变和以InP为衬底),应变层超晶格(InAs)1(InP)1(001)和与应变层超晶格的分子层相对应的应变体材料,以及无应变的体材料进行了第一原理计算,并采用冻结势方法求出了两种超晶格各分子层的平均键能。结果表明,能存在应变的情况下,异质界面两边的平均键能非常一致,且这种一致性受应变状态的影响很小,因而可以把它用来作为确定应变层超晶格价带边不连续值(△Ev)的普遍适用的参考能级。研究了应变对
关键词: 相似文献
6.
采用嵌入原子势和分子动力学方法,模拟了单晶铁在一维应变条件下由体心立方(bcc)转变为六角密排(hcp)结构的微观过程. 当应变加载至相变临界值时,hcp相开始均匀形核并沿{011}晶面长大为薄片状体系.弹性常数C31和C32在相变前被逐渐硬化,C33则在相变前出现软化行为;当体系完全相变后,上述各弹性常数显示开始随体积压缩而迅速硬化,温度效应对晶格具有软化作用,可削弱C33的硬化和软化过程;样品在压缩过程可出现孪晶结构,孪晶结构使晶格发生剪切变形.混合相中,hcp相势能比bcc相高,最大剪应力方向与bcc相反向;系统的偏应力与hcp相质量分数近似呈线性关系.
关键词:
结构转变
分子动力学
一维应变 相似文献
7.
利用Instron万能试验机与LC4超硬铝合金分离式Hopkinson压杆设备,对3种不同波阻抗的橡胶材料——炭黑母胶(Carbon Black Rubber)、硅橡胶(Silicone Rubber)和泡沫橡胶(Foam Rubber)在较大应变率范围(0.002~15 000s-1)内进行了单轴压缩实验,研究应变率对橡胶材料力学性能的影响。实验结果表明:3种橡胶的准静态与动态应力-应变曲线具有不同的应变硬化形式,且动态加载下随着应变率的增大,硬化效应逐渐增强;在准静态及高应变率(12 000~15 000 s-1)压缩下,泡沫橡胶表现出多孔类材料压缩曲线的弹性、塑性崩塌及致密化3段特征。基于Rivilin应变能模型,构建了一个应变率相关的动态本构模型,模拟结果与实验结果吻合较好,可以用于描述较大应变率范围内3种橡胶的非线性应力-应变关系。 相似文献
8.
9.
10.
通过考察两种基体泡沫Al(分别为脆性和塑性)单向压缩应力-应变曲线,探讨了其形变和能量吸收特征及机理,得到了一些与以往不同的研究结果.研究发现,与其他多孔固体材料一样,泡沫Al的压缩形变过程也经历三个区域,即线性弹性区、平台区和致密化区;泡沫Al的吸能本领随屈服强度的提高而增强;在屈服强度相近的情况下,脆性泡沫Al的吸能本领高于塑性泡沫Al;泡沫Al吸能效率峰值对应于较低的应变值(约为0.15—0.25);吸能效率峰值对基体成分和状态不敏感,随密度增加,吸能效率峰值呈下降趋势.
关键词: 相似文献
11.
12.
In this paper, we perform systematic calculations of the stress and strain
distributions in InAs/GaAs truncated pyramidal quantum dots (QDs) with
different wetting layer (WL) thickness, using the finite element method (FEM).
The stresses and strains are concentrated at the boundaries of the WL and
QDs, are reduced gradually from the boundaries to the interior, and tend to
a uniform state for the positions away from the boundaries. The maximal
strain energy density occurs at the vicinity of the interface between the WL
and the substrate. The stresses, strains and released strain energy are
reduced gradually with increasing WL thickness. The above results show that
a critical WL thickness may exist, and the stress and strain distributions
can make the growth of QDs a growth of strained three-dimensional island
when the WL thickness is above the critical value, and FEM can be applied to
investigate such nanosystems, QDs, and the relevant results are supported by
the experiments. 相似文献
13.
The anchoring properties of substrate with a grating surface are
investigated analytically. The alignment of nematic liquid
crystal (NLC) in a grating surface originates from two
mechanisms, thus the anchoring energy consists of two parts. One
originates from the interaction potential between NLC molecules
and the molecules on the substrate surface, and the other stems
from the increased elastic strain energy. Based on the two
mechanisms, the expression of anchoring energy per unit area of
a projected plane of this grating surface is deduced and called
the equivalent anchoring energy formula. Both the strength and
the easy direction of equivalent anchoring energy are a function
of the geometrical parameters (amplitude and pitch) of a grating
surface. By using this formula, the grating surface can be
replaced by its projected plane and its anchoring properties can
be described by the equivalent anchoring energy formula. 相似文献
14.
张应变GaAs1-xPx量子阱是高性能大功率半导体激光器的核心有源区,基于能带结构分析优化其结构参数具有重要的应用指导意义.首先,基于6×6 Luttinger-Kohn模型,采用有限差分法计算了张应变GaAs1-xPx量子阱的能带结构,得到了第一子带间跃迁波长固定为近800 nm时的阱宽-阱组分关系,即随着阱组分x的增加,需同时增大阱宽,且阱宽较大时靠近价带顶的是轻空穴第一子带lh1,阱宽较小时靠近价带顶的是重空穴第一子带hh1.计算并分析了导带第一子带c1到价带子带lh1和hh1的跃迁动量矩阵元.针对808 nm量子阱激光器,模拟计算了阈值增益与阱宽的关系,得到大阱宽有利于横磁模激射,小阱宽有利于横电模激射.进一步考虑了自发辐射和俄歇复合之后,模拟计算了808 nm量子阱激光器的阱宽与阈值电流密度的关系,阱宽较大时载流子对高能级子带的填充使得阈值电流密度增加,而阱宽较小时则是低的有源区光限制因子导致阈值电流密度升高,因此存在一最佳的阱宽-阱组分组合,可使阈值电流密度达到最小.本文的模拟结果可对张应变GaAs1-xPx量子阱激光器的理论分析和结构设计提供理论指导. 相似文献
15.
Strain effect on graphene nanoribbon carrier statistic in the presence of non-parabolic band structure 下载免费PDF全文
The effect of tensile uniaxial strain on the non-parabolic electronic band structure of armchair graphene nanoribbon(AGNR) is investigated.In addition,the density of states and the carrier statistic based on the tight-binding Hamiltonian are modeled analytically.It is found that the property of AGNR in the non-parabolic band region is varied by the strain.The tunable energy band gap in AGNR upon strain at the minimum energy is described for each of n-AGNR families in the non-parabolic approximation.The behavior of AGNR in the presence of strain is attributed to the breakable AGNR electronic band structure,which varies the physical properties from its normality.The linear relation between the energy gap and the electrical properties is featured to further explain the characteristic of the deformed AGNR upon strain. 相似文献
16.
In order to clarify the edge and interface effect on the adhesion energy between graphene(Gr)and its substrate,a theoretical model is proposed to study the interaction and strain distribution of Gr/Si system in terms of continuum medium mechanics and nanothermodynamics.We find that the interface separation and adhesion energy are determined by the thickness of Gr and substrate.The disturbed interaction and redistributed strain in the Gr/Si system induced by the effect of surface and interface can make the interface adhesion energy decrease with increasing thickness of Gr and diminishing thickness of Si.Moreover,our results show that the smaller area of Gr is more likely to adhere to the substrate since the edge effect improves the active energy and strain energy.Our predictions can be expected to be a guide for designing high performance of Grbased electronic devices. 相似文献
17.
《Composite Interfaces》2013,20(2):119-130
Nanosized titania and silica-supported titania (SST) were prepared by the sol–gel method using titanium tetrachloride as a titania precursor. An opposite behavior was observed in the lattice strain of titania and SST before and after transition onset point (TOP). The effect of the changes of the lattice strain on the size of nanocrystallites, the TOP, and activation energy of phase transformation from anatase to rutile is investigated. It is shown that under identical synthesis conditions, the average size of nanocrystallites in SST was less than that of pure titania. Moreover, TOP of titania was lower in pure titania sample than that of SST due to the tensile strain of pure titania vs. the compressive strain of SST at low calcination temperature. However, the activation energy of pure titania due to the compressive strain and the exponential leap of the tensile strain of SST, after TOP, was higher than that of SST. 相似文献
18.