金属丝弹性模量的测量方法研究

通过用纳米压入法和静态拉伸法对β-Ti丝、不锈钢丝以及3种NiTi丝进行弹性模量的测量。实验表明,纳米压入法弹性模量比静态拉伸法弹性模量大,并且材料的弹性模量越低,二者相差越大,其原因同试样的表面硬化层和尺寸效应有关。通过分析比较,建立了金属丝弹性模量的纳米压入法和静态拉伸法所得值之间的相关关系。     

金属纤维弹性模量的振动法测量

针对测量金属纤维弹性模量传统方法存在的局限,提出了一种用振动法测量金属纤维弹性模量的新方法。详细介绍了该方法的测量原理、测量装置、测量过程及误差分析。分别选择了钼丝和铂铱25合金纤维为测量对象,将被测材料制备成微悬臂梁试样,通过瞬态激励使悬臂梁产生短暂振荡,然后获得悬臂梁固有频率,再通过计算公式求出金属纤维材料的弹性模量。与静态拉伸法测量结果进行了比对,试验证明两者测试结果较为吻合。分析了悬臂梁长对测试结果的影响,结果表明:只有当梁长大于或等于8倍梁高(直径)时,这种影响才可忽略不计。     

梁三点弯曲法测量薄膜弹性模量

用电刷技术在不锈钢基体一侧表面上刷镀了Cu膜,用电镀技术在不锈钢基体一侧表面或双侧表面上制备Ni膜。用梁三点弯曲法在自制的设备上测量不锈钢基体以及不锈钢基体上不同厚度Cu膜和Ni膜的弹性模量E。研究表明：在测量的膜厚范围内(7μm-15μm),Cu膜和Ni膜的弹性模量E不随膜厚变化,并且接近各自块材的弹性模量。     

超声相控阵法测量材料的弹性模量

提出了一种基于超声相控阵测速的材料弹性模量测量方法。采用相控阵列的声速测量方法能获得精细的超声信号波组,从而能分析出超声信号的幅值与相位,对材料纵波声速与横波声速的测量精度可达到5位有效数字,进而能高精度地测量材料的弹性模量,以便对材料的力学性能进行无损评价。     

“敲击法”测量弹性模量的研究

超声振动系统设计及分析时要用到声速,声速计算时要用到弹性固体材料的弹性模量、密度.固体密度易测量,弹性模量较难测量.实验证明:"敲击法"测量弹性模量的原理、方法是简便有效的.     

鼓泡法测量高分子和金属薄膜弹性模量的方法探讨

在自制的鼓泡仪上对高分子薄膜和金属镍膜的弹性模量进行了测量,并研究了孔径对薄膜弹性模量测量的影响。结果表明,高分子薄膜的弹性模量为2.7±0.2GPa,孔径对薄膜弹性模量的测量没有影响;受仪器精度限制,该仪器目前尚难用于金属镍膜的弹性模量的精确测量。     

异质金属丝电弧喷涂工艺的试验研究

本文主要介绍利用电弧做热源,通过电弧喷涂的工艺方法,使不锈钢丝和铝丝瞬间同时熔化后喷射粘附在基体金属表面上,得到一种复合材质涂层。试验中通过改变送丝速度和电弧电压等参数,制备一些涂层试样,并对涂层进行了宏观和微观组织结构检测、X射线衍射分析和显微硬度测量。由试验分析结果可以得到以下结论: (1)通过调节送丝速度和电弧电压等参数,铝和钢的异丝喷涂是可以实现的;(2)涂层的颗粒大小可以通过改变工艺参数来控制;(3)铝和钢异丝喷涂层中有Fe-Al化合物生成,其硬度高于铁、铝纯金属;(4)利用电弧喷涂装置有望使异质金属丝同时熔化并发生冶金反应,从而制备具有特殊性能的金属化合物涂层。     

弹性模量与塑性变形变化规律试验研究

弹性模量是影响冲压回弹量的重要材料性能参数,在工程应用和回弹数值模拟中一般认为弹性模量为常数.而实际上,弹性模量随塑性变形的增大不断变化,因此其变化对工程中的回弹量评估和数值模拟回弹预测精度有很大的影响.本文针对在汽车和航空工业中广泛应用的铝合金和钢板,采用动力试验方法,对ST14钢及3A21、2024-T3和2A12铝合金的弹性模量在塑性变形中的变化规律进行了试验研究,得到了弹性模量值与等效塑性应变的变化规律,并采用分段线性函数进行了描述.研究结果为进一步研究弹性模量随塑性变形的变化规律及探讨其本质提供了依据,也预示了一种提高有限元回弹预测精度的解决办法.     

金属丝电弧熔化喷射涂层法

英国的金属喷镀公司新近开发成功一项新技术——电弧熔化喷射涂层法（Arcspray）,该法是将电弧熔化的一对金属丝熔融金属通过一个压缩空气喷咀喷射到待涂层的工件表面上。喷涂于工件表面上的熔融金属层凝固后即形成致密牢固附着的涂层,适合于防腐蚀或对金属制品的修补,也可用于提高制品的抗磨性、导电性或导热性。     

Tensile testing as a method for determining the Young''s modulus of thin hard coatings

The present paper describes and evaluates a tensile testing method for determination of the Young's modulus of thin hard coatings. When applied to PVD TiN and NbN coatings on stainless steel foils, the elastic modulus obtained through force—strain plots ranged between 380 and 425 GPa for TiN coatings, and was 350 GPa for the single NbN coating tested. It is concluded that the method is easy to perform and allows reliable determination of the Young's modulus of thin hard coatings, and that it can be applied to almost any kind of coating on a wide range of substrate materials.     

弛豫铁电体Pb(Mg1/3Nb2/3)O3-PbTiO3的相变

测量了(1-x％)镁铌酸铅-x％钛酸铅(1≤X≤11)(简称PMNTx)陶瓷样品的介电常数、内耗和Young’s模量．观测到在Tm温度附近,即在介电常数达到最大值时,出现一个内耗峰,并且模量发生软化．这反映了极化纳米微畴的弛豫．对于PMNTx(5≤x≤11)的样品,在Tm温度以下的某个温度出现附加的内耗峰和Young’s模量的异常,表明样品中发生了自发的弛豫铁电到铁电(简称R-F)的相变,对R-F相变的机制进行了讨论．     

板材杨氏模量对称三点弯曲测试方法及测试装置

金属板材在弹性对称三点弯曲时最大挠度与集中力呈线性比例关系,由该关系可求出板材的杨氏模量。文章提出利用对称三点弯曲的原理测量金属板材杨氏模量的方法,并设计加工了相应的试验装置,该装置结构简单,制作成本低,挠度测量采用百分表,测量精度高。实测了1mm厚铝板和铜板及3.1mm厚钢板的杨氏模量,测量结果稳定可靠。     

孕镶金刚石工具中金刚石与胎体间机械包镶力的研究

孕镶金刚石工具中,胎体对金刚石的包镶力来自金刚石与胎体间的冶金反应造成的冶金包镶力以及金刚石与胎体间的机械包镶力。本文研究了机械包镶力产生的原因和计算方法,计算了常用胎体所产生的机械包镶力的大小为380～560MPa。通过测定胎体的弹性模量表明,提高胎体弹性模量42％,不考虑胎体的相变,即可增大机械包镶力47％。     

A constitutive model for spring-back prediction in which the change of Young's modulus with plastic deformation is considered

In order to improve the prediction capability of spring-back in the computational analysis of sheet metal forming processes, a stress–strain constitutive formulation of non-linear combined hardening rule has been proposed in this paper according to non-linear kinematic hardening theory of Lemaitre and Chaboche and Hill's 1948 anisotropic yielding function. Traditionally, Young's modulus is considered as a constant in engineering application and numerical simulation. In fact, it decreases with plastic deformation. So the effect of the change of Young's modulus with plastic strain on spring-back is considered in the constitutive model. The algorithm of stress update is elastic prediction, plastic correcting and radial returning. Numerical results and experimental results show that the proposed constitutive model significantly improves the prediction accuracy of spring-back.     

On the relationship between plastic zone radius and maximum depth during nanoindentation

The relationship between plastic zone size and plastic depth during indentation has been studied by a number of workers and an expression relating the plastic zone radius to the residual indentation depth (assumed to be the plastic depth) was developed by Lawn et al. [B.R. Lawn, A.G. Evans and D.B. Marshall, J. Am. Ceram. Soc. 63 (1980)198.] based on microindentation testing. In this study, the relationship between the plastic zone radius and residual indentation depth was examined using finite element analysis for conical indentation in elastic-perfectly-plastic bulk materials. The simulations show that the Lawn method overestimates the plastic zone size for different materials with a wide range of Young's modulus over hardness ratio and for indenters with different geometries and it does not consider tip rounding effects. Therefore, an analytical expression is outlined which agrees well with finite element data. For practical application, the relationship between the radius of the plastic deformation zone and the maximum penetration depth is developed here which has been used to modify the energy-based model developed at Newcastle University to predict the hardness and Young's modulus of coated systems. It is found that the new relationship is easy to apply and predictions of the hardness and Young's modulus of coated glass show good agreement with experimental results.     

Magnetoelastic performance of 《110》 aligned polycrystalline Tb0.3Dy0.7Fe2

The magnetoelasfic performance of <110> aligned polycrystalline Tt0.3Dy0.7Fe2 was investigated.It has been round that the strata-stress curve is nearly linear without magnetic field,reflecting the purely mechanical elastic properties of the Tb0.3Dy0.7Fe2 rod.The strain-stress curve exhibits a complex behavior in magnetic field and can be divided into three stages.The different stages are explained with magneticdomains in the Tb0.3Dy0.7Fe2 rod alloy and the higher the magnetic field,the larger the stress to switch domains.The Young's modulus is also obtained from measuring the strain-stress curve and the variability of Young's modulus as the strain is analyzed.     

Magnetoelastic performance of 〈110〉 aligned polycrystalline Tb0.3Dy0.7Fe2

The magnetoelastic performance of <110> aligned polycrystalline Tb_0.3Dy_0.7Fe₂ was investigated. It has been found that the strain-stress curve is nearly linear without magnetic field, reflecting the purely mechanical elastic properties of the Tb_0.3Dy_0.7Fe₂ rod. The strain-stress curve exhibits a complex behavior in magnetic field and can be divided into three stages. The different stages are explained with magnetic domains in the Tb_0.3Dy_0.7Fe₂ rod alloy and the higher the magnetic field, the larger the stress to switch domains. The Young's modulus is also obtained from measuring the strain-stress curve and the variability of Young's modulus as the strain is analyzed.     

Nd-Fe-B磁体杨氏模量随温度的变化

为揭示快淬热压磁体热应变织构产生的根源,我们对合金机械性能随温度的变化进行了系统研究。前文报道了Nd-Fe-B磁体的热膨胀和硬度随温度的变化,本文则着重报道在室温到800℃温区内,Nd-Fe-B磁体的杨氏模量随温度的变化,以展示晶体刚度各向异性和塑性流变特性对热应变织构形成的可能贡献。一般而言,合金的杨氏模量是结构不敏感的参量,即它与合金内部显微组织以及合金成分的微调无关。它主要反映合金内部原子之间的键合,故具