Numerical simulation of microstructure formation ofAZ91 using mCA method

A stochastic model for simulating the microstructure formation of Mg alloy AZ91 during solidification was developed based on the finite element method（FEM） for macroscopic model of heat transfer calculation and a modified Cellular Automaton （mCA） for microscopic modeling of nucleation, growth of crystal. In this model, the effect of solute redistribution, interface curvature and preferred orientation was considered. A numerical simulation was developed with C＋＋ program language. The computation was carded out to understand the effect of varying processing parameters, such as nucleation parameters and heat transfer coefficient, on the microstructure formation of AZ91. The result of simulation was displayed on screen.     

共晶自生复合材料的晶形转变

自生复合材料的晶形转变受到成分过冷与曲面过冷两个因素的控制.非金属相具有较大的熔化熵且易形成小平面是改变领先相的因素,而领先相的改变则可能是晶形转变的根本原因.     

压入深度与膜厚对薄膜与基体复合硬度及弹性模量的影响

根据高华建的复合弹性模量模型，提出了用一个测点的载荷-位移曲线计算整个压入深度内薄膜和基体复合硬度分布的方法，探讨了压入深度与膜厚对硬度与弹性模量测量值的影响，指出可由膜-基复合性能反推膜本身的性能。     

熔模铸造型壳抗弯弹性模量的研究

依据材料力学、陶瓷材料的有关理论和方法,分别对水玻璃型壳、硅溶胶型壳及其复合型壳在不同温度时的抗弯弹性模量进行了测试研究.结果表明,耐火材料、温度对型壳的弹性模量有较大的影响,硅溶胶型壳和复合型壳的弹性模量值比水玻璃型壳的大.     

大型弹簧钢片开裂原因分析

为保证大型弹簧钢片在热处理过程中，不发生开裂和翘起度超差，重新制订了热处理工艺。通过增加高温回火、降低淬火温度、加快冷却速度等手段，获得了最好的效果。     

轴类零件校直工艺广义预测多步算法研究

本文基于行程控制的轴类零件校直工艺公式 ,构建了模拟轴类零件校直工艺过程的广义预测控制模型 ,应用广义预测算法 ,实现了对轴类零件弹塑性非线性残余变形的均匀控制 ,实验研究表明 ,该方法能满足精密校直要求 ,并且随着控制步长的增多 ,控制效果显著。     

Effect of cold spray deposition of a titanium coating on fatigue behavior of a titanium alloy

The deposition of titanium on a titanium alloy substrate is being examined for potential use as a surface treatment for medical prostheses. A Ti6Al4V alloy was coated with pure titanium by cold gas dynamic spraying. Coatings were deposited onto samples with two different surface preparation methods (as-received and grit-blasted). The fatigue life of the as-received and grit-blasted materials, both before and after coating, was measured with a rotating-bend fatigue rig. A 15% reduction in fatigue endurance limit was observed after application of the coating to the as-received substrate, but no significant reduction was observed on its application to the grit-blasted substrate. The reduction in fatigue endurance limit has been related to the substrate-coating interface properties, the elastic modulus, and the residual stress states. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference, (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, 2006.     

AB INITIO CALCULATION OF THE ELASTIC AND OPTICAL PROPERTIES OF Al_3Sc COMPOUND

The ab initio method has been performed to explore the elastic and optical properties of Al3Sc compound, based on a plane wave pseudopotential method. It can be seen that the calculated equilibrium lattice parameter and elastic constants are in reasonable agreement with the previous experimental data. The elastic constants satisfy the requirement for mechanical stability in the cubic structure of the Al3Sc compound. The optical property calculations show that a strong absorptive peak exists from 0-15eV and a relative small absorptive peak exists around 30eV. The form is caused by the optical transitions between high s, p, and d bands, and the latter results from the optical transitions from high s, p, and d bands to the low 2p band.     

在纳米压入仪上进行悬臂梁法测量弹性模量的影响因素分析

对在纳米压入仪上进行悬臂梁法测量弹性模量的主要影响因素进行了综合分析,主要包括加载系统悬置弹簧刚度、压头压入、梁沿截面宽度方向挠曲、梁支座附加挠曲等影响。在考虑这些因素的基础上,得到了悬臂梁的有效挠度,利用有效挠度与载荷之间的关系,评价悬臂梁材料的弹性模量。对单晶硅(100)悬臂梁试样进行了实验,得到其弹性模量为155GPa±9.5%GPa,与参考文献值符合较好。表明在纳米压入仪上进行悬臂梁法测量,只有综合这些影响因素后,才能获得有效、准确的弹性模量测量结果。