Strain rate sensitivity of tensile properties in high Nb containing TiAl alloys

The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.     

Strain rate sensitivity of the commercial aluminum alloy AA5182-O

The mechanical behavior of the commercial aluminum alloy AA5182-O is investigated at temperatures ranging from −120 to 150 °C and strain rates from 10⁻⁶ to 10⁻¹ s⁻¹. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the strain rate and temperature range in which dynamic strain aging leads to negative strain rate sensitivity is mapped. The effect of dynamic strain aging on ductility and strain hardening is investigated. The sensitivity of the measured quantities to the experimental method employed and their dependence on grain shape are discussed. The experimental data are compared with the predictions of a model constructed based on a recently proposed mechanism for dynamic strain ageing. The mechanism is based on the effect solute clustering at forest dislocations has on the strength of dislocation junctions. The model is shown to reproduce qualitatively the experimental trends.     

Fatigue damage accumulation of cold expanded hole in aluminum alloys subjected to block loading

Fatigue damage accumulation of cold expanded hole in aluminum alloys used in land transportation components was investigated. Tests were carried out using pre-cracked SENT specimens and inserting an expanded hole at the crack tip. The degree of the cold expansion was chosen equal to 4.3%. Tests were performed in two and four block loading under constant amplitude. Two sequences were compared.The increasing and the decreasing magnitude were compared. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the ‘model of the damage stress’, which take into account of the loading history, yields a good estimation of the experimental results. Moreover, the error is minimized in comparison to the Miner's model.     

Martensitic stabilization and defects induced by deformation in TiNi shape memory alloys

Martensitic stabilization caused by deformation in a TiNi shape memory alloy was studied.Special attention was paid to the deformed microstructures to identify the cause of martensitic stabilization.Martensitic stabilization was demonstrated by differential scanning calorimetry for the tensioned TiNi shape memory alloy.Transmission electron microscopy revealed that antiphase boundaries were formed because of the fourfold dissociation of[110]B19'super lattice dislocations and were preserved after reverse transformation due to the lattice correspondence.Martensitic stabilization was attributed to dislocations induced by deformation,which reduced the ordering degree of the microstructure,spoiled the reverse path from martensite to parent phase compared with thermoelastic transformation,and imposed resistance on phase transformation through the stress field.     

大塑性变形制备超细晶生物医用钛合金的研究进展

生物医用钛合金具有高强度、良好的耐蚀性能、较低的弹性模量、优异的生物相容性,已成为具有广阔应用前景的医用金属材料之一.与传统医用钛合金相比,超细晶医用钛合金具有更高的强度与更好的疲劳性能以及耐腐蚀性能.此外,超细晶钛合金可诱导骨组织向内生长,增加界面结合强度,加快骨修复进程,在硬组织修复材料领域具有广阔的应用前景.阐述了各种大塑性变形（Severe Plastic Deformation）法制备超细晶生物医用钛合金的研究状况与最新进展,指出了SPD法制备医用钛合金中存在的技术问题和发展方向,并展望了利用SPD法对生物医用钛合金改性将成为生物医用材料的研究热点.     

ZL205A高强度铝铜合金的铸造及热处理

探讨了ＺＬＮ２０５Ａ高强度铝铜合金的铸造性能和热处理工艺方法，阐述了ＺＬ２０５Ａ铝铜合金在Ｔ５热处理时，如何才能达到机械性能的工艺方法。     

侧链多阳离子型氟化聚芴醚阴离子交换膜及其全钒液流电池性能

阳离子基团的分布对阴离子交换膜的微观相态和阴离子传导率有显著的影响.为开发全钒液流电池用高性能阴离子交换膜,本文通过向含有二甲胺基团的氟化聚芴醚前驱体接枝含阳离子烷基链的方式,合成了具有相似离子交换容量的一系列侧链多阳离子型氟化聚芴醚.实验结果表明,多阳离子侧链的引入能促进微观相分离的形成并提升阴离子传导率.同时,侧链...     

Phase equilibria in the Au–In–Sn ternary system

Phase equilibria of the Au–In–Sn system have been investigated by Differential Scanning Calorimetry (DSC), metallographic examination, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) measurements. The 130 ^°C isothermal section of the phase diagram was studied. The ternary diagram shows six three-phase fields, and one ternary Au₄In₃Sn₃ phase, which melts incongruently at 382 ^°C and shows a homogeneity range between 21 and about 30 at.% In, at constant Au/Sn ratio.     

Euro PM2007 congress and exhibition

Abstract

Threatened with bureaucratic over-regulation under the EU's newly enacted REACH legislation, and other competitive challenges, the large tonnage section of the European PM industry did not seem to be facing a rosy future as it met in the Ville Rose city of Toulouse. Nevertheless, the EPMA was seen as having a key role in moving the industry forward and resisting the pressures from the large end users, low cost (Asian) producers, and competing technologies. Europe still leads the world in the manufacture of hard materials, but China is expected to overtake Europe in tungsten carbide and diamond tools production within the next 3–5 years. European sales of metal injection moulded parts continue to grow strongly, doubling in value to E140 million between 1997 and 2003. PM research in Europe is very active, with 40 universities and institutes and over 500 researchers involved. These provided the large majority of the European presentations at PM2007.