Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds

Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness.     

W-Ni-Cu高比重合金注射成形烧结收缩及性能的研究

研究了W-Ni-Cu高比重合金注射成形工艺过程收缩率和性能。比较了模具尺寸、注射坯尺寸、烧结坯尺寸，及烧结阶段各方向收缩率的关系，发现实际收缩与理论预测收缩率较为一致，但在厚度方向存在与其他方向收缩不一致的情形，这与由重力作用产生的塑料流动有关；还探讨了烧结坯密度与烧结条件的关系，测定了烧结坯的力学性能及断口形貌、金相组织，烧结坯在1400℃，90min烧结达到了99％的相对密度，断裂强度600MPa以上。     

国内钛合金近几年学术研究进展

在钛合金研发受到高度重视的同时,相关钛合金的基础研究国内也较重视,取得了较好的成绩,如发展的近β锻造技术、准β锻造技术、三态组织、阻燃机理、低温变形机理、原子与空位的交互作用等等。本文综述了国内钛合金近几年的学术研究进展。     

Ti-45Al-10Nb合金的高温氧化行为

研究了Ti—45A1—10Nb(原子分数，％)合金在800-960℃在氧气和空气中的氧化行为．结果表明，该合金具有较好的高温抗氧化性能，其氧化增重速率与铁基耐热不锈钢相似或略优．与Ti—50A1合金相反，Ti-45A1-10Nb合金在空气中的氧化增重速率明显低于在纯氧中的氧化增重速率．X射线衍射与能谱分析表明，Ti-45Al一10Nb合金在氧气中的氧化产物主要有TiO2和Al2O3，但在空气中的氧化产物中有TiN相．这是降低氧化速率的主要原因，同时，合金元素Nb稳定了氧化层中的TiN相，因而提高了合金在空气中的抗氧化性能．     

Monte Carlo simulation of hydrogen absorption in palladium and palladium–silver alloys

A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition Pd_xAg_1−x (x=0.7–0.8) under H₂ pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys.     

Properties of Quaternary Alloy Magnetic Semiconductor (InGaMn)As Grown on InP

We have studied properties of quaternary alloy magnetic semiconductor (InGaMn)As grown on InP substrates by low-temperature molecular-beam epitaxy (LT-MBE). A large MCD peak whose intensity is larger than 500 mdeg for (InGaMn)As was observed. This peak intensity was about three times larger than that of typical (GaMn)As films. Relatively high Curie temperature of 83 K of [(In_0.53Ga_0.47)_0.88Mn_0.12]As was observed by Hall measurements. The carrier concentration of [(In_0.53Ga_0.47)_0.88Mn_0.12]As was estimated to be more than 1.0 × 10²¹ cm^–3 by using the Curie–Weiss fitting of the Hall coefficient R _H, indicating that more than 40% of Mn atoms are activated. This means that (InGaMn)As has a higher activation ratio of Mn as acceptors than (GaMn)As.     

Effect of heat treatments on tensile properties and microstructures of wrought Mg−Zn−Zr-RE alloys

The effect of heat treatments on the tensile properties and microstructures of wrought Mg–Zn–Zr-Rare earth alloys MB25 and MB26 have been studied in this paper. It was shown that the homogenization of the cast ingots decreased the strength of the extruded bars because some grain boundary phases were dissolved during the process of this treatment, while the ageing treatment of the extruded bars increased the strength due to the dispersive precipitation of MgZn₂ phase. The quenching + ageing treatments of the extruded bars decreases the strength and plasticity because of the growing up of the grains.Abbreviations ED electron diffraction - GB grain boundary - RE rare earth - TEM transmission electron microscope     

含钡合金在钢液中的脱氧行为研究

在MoSi2炉上采用MgO质坩蜗对钢管进行了含钡合金脱氧行为的研究。实验中钡系合金主要选取SiAUBa、SiCaBa、SiAlBaCa、SiAlBeCaSr及用于钙处理的SiCa包芯线，选用Al作为对比脱氧剂，考察了钡系合金脱氧的全氧含量，脱氧产物的分布、尺寸和形貌，探讨了钡系合金脱氧和对夹杂物变性作用的机理。     

SiCp/2024复合材料的氢脆敏感性研究

在浸泡、阴极极化、阴极极化同时迭加拉伸变形、添加As₂O₃毒化剂等常见致氢条件下,通过慢应变速率拉伸试验研究了SiC_p/2024复合材料的力学性能,考察了断口形貌.测定了该材料在按几种常用充氢条件充氢后的氢含量.发现虽然强烈阴极极化使材料力学性能下降,但其原因在于阴极极化引起的碱性腐蚀,与氢脆无关.获得了不同于前人研究的新结论:在本文试验条件下SiC_p/2024材料不发生氢脆,也不发生不可逆氢损伤,其原因与该材料难以充入氢有关.     

铜镍锰钴应变电阻合金的研究

为解决我国箔式应变计引进生产线用箔材国产化的问题，本所自行设计研制了一种新型的温度自补偿铜镍锰钴合金。该合金具有良好的性能复现性和工艺稳定性，制片后的各项性能十分优异，特别是其平均热输出系数Ｃｔ和对试件材料的适应性明显优于进口箔，是制造高精度箔式应变计的理想材料。