基片负偏压对Cu膜纳米压入硬度及微观结构的影响

测试了不同溅射偏压下Cu膜的纳米压入硬度，探讨了溅射偏压、残余应力及压痕尺寸效应对Cu膜硬度的影响。结果表明，随着溅射偏压的增大，薄膜晶粒尺寸及残余压应力均减小，导致薄膜的硬度增大，并在-80V达到最大值，随后有所降低。同时薄膜中的压痕尺寸效应对薄膜硬度随压入深度的分布有很大的影响。     

加载速率对Al膜纳米压人蠕变性能的影响

纳米压入仪对Si片上多晶Al膜进行的压入蠕变实验表明，加载方式对Al膜的蠕变性能有明显影响随加载速率和载荷的增大，Al膜的总蠕变量和应力指数均有较大升高．且蠕变初期可能存在异常高蠕变率．分析认为这与是加载过程中未及发生的塑性变形的持续释放有关．对于确定的薄膜材料及组织结构，加载过程中积攒的塑性变形量及其释放速率将影响不同加载条件下的总蠕变量和应力指数。     

去应力退火对Cu膜纳米压入蠕变性能影响的研究

在JGP560V磁控溅射镀膜设备上镀制多晶Cu膜，选取沉积态和经过3h去应力退火的退火态两种Cu膜，利用纳米压入技术测量了其室温下的蠕变性能。试验结果显示去应力退火后的Cu膜残余应力反而升高；且其室温蠕变性能与沉积态的Cu膜有很大的不同；随保载载荷升高，两种状态下的Cu膜蠕变应力指数均升高。分析认为这是由于退火造成膜基体系内应力的变化，同时减少了薄膜中的各种点缺陷和线缺陷，从而改变了Cu膜蠕变性能的结果。     

多晶铜膜纳米压入蠕变性能

在JGP560V磁控溅射镀膜设备上镀制多晶铜膜,利用纳米压入技术测量了其室温下的蠕变性能.结果表明:由于不同加载方式下,材料加工硬化程度的不同造成了应力指数的差异,因而,不同加载方式对测得的铜膜蠕变应力指数有比较大的影响;由于材料在高载荷时在压头下端产生更多的位错,阻碍了压头的压入,使蠕变率降低,因而,随着保载载荷的升高,蠕变应力指数变大.     

加载速率对Al膜纳米压入蠕变性能的影响

纳米压入仪对Si片上晶Al膜进行的压入蠕变实验表明,加载方式对Al膜的蠕变性能有明显影响.随加载速率和载荷的增大, Al膜的总蠕变量和应力指数均有较大升高 且蠕变初期可能存在异常高蠕变率.分析认为这与是加载过程中未及发生的塑性变形的持续释放有关.对于确定的薄膜材荆及组织结构,加载过程中积攒的塑性变形量及其释放速率将影响不同加载条件下的总蠕变量和应力指数.     

纳米压痕法测量Cu的室温蠕变速率敏感指数

介绍一种测量室温蠕变速率敏感指数m的新方法。即通过纳米压痕仪精确测量压头的压入位移h和材料的硬度值来计算m值。用该法分别测得单晶Cu(123)压痕蠕变的m的平均值约为0.0045;多晶Cu和纳米晶Cu(晶粒尺寸为30nm)的m的平均值分别为0.007和0.0094。压痕蠕变曲线与传统的单轴蠕变曲线十分相似;室温m的平均值与加载条件无关,而由材料的微观结构决定。     

梯度纳晶镍拉压不对称性分子动力学研究

基于分子动力学模拟研究了在拉伸和压缩载荷下梯度纳晶镍的力学性能和微观变形机制。结果表明，梯度纳晶镍在压缩载荷下的平均流动应力大于拉伸载荷下的平均流动应力，反映出较为明显的拉压不对称性，同时拉压不对称性随着晶粒尺寸梯度的增大越发明显，在晶粒梯度为0.230时，应力拉压不对称性达到最大，此后随晶粒梯度的增大而逐渐减小。通过统计发现，梯度纳晶镍在变形过程中位错运动和位错密度也存在拉压不对称性。进一步定量分析得知，位错密度拉压不对称性随晶粒梯度的变化趋势与平均流动应力的应力拉压不对称性一致，证实了位错运动是导致应力拉压不对称性的直接原因。     

固溶态和时效态7075铝合金的微纳米压痕力学行为

采用微纳米压痕实验研究了固溶态和时效态7075铝合金的力学性能和压痕蠕变行为，获得了其力学本构方程、应力-应变曲线和蠕变应力指数。结果表明：两种状态铝合金的硬度和弹性模量均随着载荷的增大而减小，并在压痕深度小于1μm时表现出明显的尺寸效应。固溶态和时效态铝合金的屈服强度分别为446 MPa和497 MPa,抗拉强度分别为594 MPa和691 MPa。两种状态合金的最大蠕变深度和蠕变应力指数变化趋势相似，均随载荷和加载速率的增大而增大。     

磁控溅射Cu膜屈服强度的有限元计算

采用离子辅助轰击共溅射设备，在Si基体的(111)晶面上制得了所需的铜膜。采用纳米压入实验，获得不同退火温度下Cu膜的弹性模量和硬度。再在纳米压入实验的基础上，结合有限元模型计算不同退火温度下磁控溅射得到的Cu膜屈服强度。发现Cu膜的屈服强度远高于整体Cu材料的屈服强度，并且退火温度对薄膜的屈服强度影响很大。通过XRD测量发现其主要原因是退火改变了晶粒尺寸和多晶Cu膜的晶粒取向分布，而导致Cu膜屈服强度的降低。     

Sn-0．7Cu无铅钎料的压入蠕变行为研究

采用自制的蠕变装置研究Sn-0.7Cu合金钎料在温度为60～120 ℃,压力为30～50 MPa下的压入蠕变性能,并利用SEM和XRD对合金蠕变前后组织的变化进行分析.结果表明,随温度和应力的增加,合金的蠕变速率增大,稳态蠕变速率符合半经验公式,并得出了该合金的本构方程.通过对其蠕变后应力指数、蠕变激活能及显微组织变化的分析,压入蠕变变形机制主要由位错攀移引起.     

The investigation of creep of electroplated Sn and Ni-Sn coating on copper at room temperature by nanoindentation

Sn and Sn-based alloy coatings (such as Ni-Sn) are important electrode materials in lithium ion batteries. The mechanical performance of such coatings is essential because they undergo severe volume change induced stress during charge-discharge cycling. As Ni-Sn and Sn anode materials will operate for long periods under stress during charge-discharge cycling at or near room temperature time-dependent relaxation mechanisms such as creep may take place. In this study, the nanoindentation creep of these materials at room temperature (RT) has been investigated. It was found that the creep very easily reaches exhaustion for Ni-Sn and the copper substrate even at high load holds and thus both exhibit a high stress exponent. For low melting temperature material such as Sn the behaviour is different; the stress exponent obtained at RT is around 3 to 8 which is consistent with conventional creep tests. The creep behaviour of an as-deposited polycrystalline Sn thin film with a rough surface strongly depends on its microstructure which makes the nanoindentation creep analysis much more complex than in single crystal materials or polycrystalline bulk materials with large grain size. The microstructural influence on creep mechanisms in Sn films is highlighted in this paper.     

纳米压痕法测量锌铝钎料的室温蠕变应力指数

利用纳米压痕技术,采用恒加载速率法,研究了Zn-22Al和Zn-22Al-0.03Ti钎料的室温蠕变行为,并对相关数据进行了测量和计算.结果表明,室温时任一载荷条件下保载时,钎料均发生了明显的蠕变行为.其中Zn-22Al-0.03Ti钎料的压入深度和蠕变位移均小于Zn-22Al钎料,最大差值分别为15.68％和26.87％.相同保载时间不同载荷保载时,两种钎料的蠕变位移均有较大差异.通过拟合计算分别获得了两种钎料室温时的蠕变应力指数,Zn-22Al-0.03Ti较Zn-22Al提高了35.79％.分析认为,Ti元素的添加导致了Zn-22Al钎料晶粒的细化,从而产生了更多的晶界是导致钎料室温抗蠕变能力提高的主要原因.     

Zr基块体金属玻璃蠕变行为的纳米压痕研究

在本工作中，通过纳米压痕实验研究了加载速率和保载时间对(Zr0.6336Cu0.1452Ni0.1012Al0.12)97.4Er2.6块体金属玻璃（BMG）的蠕变变形行为的影响。实验结果表明，合金试样的蠕变位移随着加载速率或保载时间的增加而增大。另一方面，合金样品的硬度（H）也随着加载速率或保载时间的增加而降低。合金试样在纳米压痕过程中具有尺寸效应，合金试样的硬度随着压痕深度的增加而降低。合金试样在纳米压痕过程中具有锯齿流动现象，并且该现象具有速率依赖性。具体而言，随着加载速率的减小，锯齿流动现象更加明显。合金试样的蠕变应力指数随着加载速率或保载时间的增加而减小。     

Dependence of strain rate sensitivity upon deformed microstructures in nanocrystalline Cu

The creep behavior of nanocrystalline copper was experimentally characterized with nanoindentation using two sequential regimes, i.e., loading and holding. Significantly enhanced strain rate sensitivity was found within an unusually narrow range of creep rate in the holding regime, which is attributed to the deformed microstructure generated during the loading regime. By quantitatively analyzing the creep rate and rate sensitivity exponent of NC Cu in the holding regime, both the grain boundary sliding (GBS) and dislocation activities are found to be responsible for the observed abnormal behavior, with the contribution of GBS decreasing with increasing grain size and increasing with decreasing loading strain rate. These findings provide a potential way of adjusting the mechanical properties of nanocrystalline metals by pre-straining.     

The flow stress in polycrystalline films: Dimensional constraints and strengthening effects

An analytical model is presented in order to derive a general expression for the flow stress in polycrystalline films which encompasses and correlates dimensional constraints and strengthening effects. The model is based on the Thompson approach, which is extended to take into account both different grain aspect ratios and distinct strengthening contributions. It allows an accurate prediction of the growth textures in polycrystalline CdTe thick films when grain growth is driven by strain energy minimization. The model also matches the experimental data concerning the grain size and film thickness dependences of the yield stress in polycrystalline Cu thin films either deposited on a substrate or freestanding. Interestingly, the yield stress is found to be fitted by a modified Hall–Petch relation resulting in a d⁻ⁿ dependence in which the exponent n varies between ½ and 1 as a function of the grain size for a given thickness.     

无铅焊点及其内部金属间化合物的力学性能研究

采用纳米压痕技术对无铅焊点(Sn3.0Ag0.5Cu、Sn0.7Cu和Sn3.5Ag)及其内部界面金属间化合物(intermetallic compound,IMC)的力学性能进行测试。根据实际工业工艺流程制备无铅焊点试样;利用接触刚度连续测量(CSM)技术对焊点及内部IMC层进行测试,得到IMC层及无铅焊点的弹性模量、硬度等力学性能参数,并根据载荷-位移曲线的保载阶段确定蠕变应力指数。结果表明,Sn0.7Cu的IMC层的弹性模量和蠕变应力指数为无铅焊点的2.03和6.73倍;对无铅焊点的可靠性评估中,将IMC层的影响考虑进去使得结果更为合理。     

Discrete and continuous deformation during nanoindentation of thin films

This paper describes nanoindentation experiments on thin films of polycrystalline Al of known texture and different thicknesses, and of single crystal Al of different crystallographic orientations. Both single-crystalline and polycrystalline films, 400–1000 nm in thickness, are found to exhibit multiple bursts of indenter penetration displacement, h, at approximately constant indentation loads, P. Recent results from the nanoindentation studies of Suresh et al. (Suresh, S., Nieh T.-G. and Choi, B.W., Scripta mater., 1999, 41, 951) along with new microscopy observations of thin films of polycrystalline Cu on Si substrates are also examined in an attempt to extract some general trends on the discrete and continuous deformation processes. The onset of the first displacement burst, which is essentially independent of film thickness, appears to occur when the computed maximum shear stress at the indenter tip approaches the theoretical shear strength of the metal films for all the cases examined. It is reasoned that these displacement bursts are triggered by the nucleation of dislocations in the thin films. A simple model to estimate the size of the prismatic dislocation loops is presented along with observations of deformation using transmission electron microscopy and atomic force microscopy. It is demonstrated that the response of the nanoindented film is composed of purely elastic behavior with intermittent microplasticity. The overall plastic response of the metal films, as determined from nanoindentation, is shown to scale with film thickness, in qualitative agreement with the trends seen in wafer curvature or X-ray diffraction measurements.