Leaded brass rods C 38500 for automatic machining operations: A technical report

C 38500 is a widely used copper alloy with a great variety of applications from decoration and architecture to mechanical/electrical engineering. The chemical composition of this alloy offers superior machinability and subsequently increased productivity in high-speed machining and manufacturing processes. In European countries, this alloy is used primarily as free cutting brass (CW 614N according to EN 12164: 1998), similar to C 36000 alloy, which is used also for thread rolling. The lower percentage of Cu compared to C 36000 (nominal 58% instead of 61%) decreases the cost of the raw materials. This paper reports the principal aspects of microstructure, mechanical properties, and machinability of this alloy in relation to the industrial manufacturing process used.     

热处理对Ag—15Al固溶体短程有序度的影响

研究了热处理对Ag-15Al(at％)固溶体合金电阻率和有序参数的影响,由X射线衍射分析表明,合金的短程序转变不是Ag_3Al化合物型的δ第二相的形成,而是α-Ag-Al固溶体原子的有序排列。     

工程机械用800MPa低合金高强度钢焊接接头断裂韧性评价

对调质状态800MPa低合金高强度钢及其焊接接头进行了系列温度的断裂韧性测试,讨论不同焊接方法对焊接接头断裂韧性的影响。发现板材的轧制方向对断裂韧性影响显著,LT方向试件的断裂韧性远超过TL方向试件的断裂韧性。在-60℃以上,母材处于上平台延性断裂范畴。在-80℃,裂纹扩展过程中有延脆断裂模式的转变。焊条电弧焊焊缝的断裂韧性与气体保护焊焊缝的断裂韧性相当。尽管常温下焊缝金属的断裂韧性甚至优于母材,但随着试验温度的降低,焊缝金属的断裂韧性迅速下降。在-20℃已发生断裂模式转变,这在结构服役时要引起重视。本研究为大型工程机械的断裂安全评定奠定了基础。     

表面氧化层对TiMn1.25Cr0.25储氢合金活化性能的影响

通过TiMn1.25Cr0.25合金粉活化前在空气中暴露不同的时间,探讨了表面氧化层的形成对其活化性能的影响。活化测试结果表明：合金的活化难度随着合金在空气中暴露时间的延长而加大。俄歇电子能谱(AES)结果表明,在空气中暴露后的合金表面形成了一层大约6nm-10nm厚的表面氧化层,正是这层氧化层的形成加大了合金的活化难度。扫描电镜(SEM)结果表明合金的活化过程与合金的碎化有着密切的联系。     

Thermodynamic reassessment of the Cd−Zn system

The Cd−Zn system has been thermodynamically reassessed with the CALPHAD method by combining more recent experimental data, in particular the activities of zinc in the liquid phase. A good agreement is obtained between the calculated and experimental thermodynamic parameters as well asphase boundaries.     

A THERMODYNAMIC INVESTIGATION ON SPINODAL DECOMPOSITION BOUNDARY IN Cu－Ti ALLOYS

ＡＴＨＥＲＭＯＤＹＮＡＭＩＣＩＮＶＥＳＴＩＧＡＴＩＯＮＯＮＳＰＩＮＯＤＡＬＤＥＣＯＭＰＯＳＩＴＩＯＮＢＯＵＮＤＡＲＹＩＮＣｕ－ＴｉＡＬＬＯＹＳ￥ＷｅｉＹｉｎｇｈｕｉ；ＷａｎｇＸｉａｏｔｉａｎ（ＩｎｓｔｉｔｕｔｅｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎ...     

基于DDS的水声通信信号发生器的研究

为了满足UUV间实时通信的需要,设计了一种基于DDS技术的水声通信信号发生器.该信号发生器以ADSP-TS101和FPGA为核心,配以外围扩展电路,能够实时产生4FSK和QDPSK通信信号,具有较强的灵活性和可扩展性.硬件试验结果表明该信号发生器精度高,能够获得很好的数字调制波形,证明可以应用于水下无线通信.     

计算机曲线拟合求解析氢反应的动力学参数

应用电化学稳态极化方法,研究1M NaOH电解液中镍硫合金电极表面析氢反应电催化活性与沉积层中含硫量之间的关系.根据析氢反应机理,用理论电化学极化方程拟合实验稳态极化曲线,得到不同含硫量的镍硫合金电极表面氢原子吸附和脱附反应的速率常数、反应对称系数等动力学参数.