Mn含量对Cu-Mn合金结构与性能的影响

基于Cu-Mn中间层可改善Cu与CuCrZr合金的连接性能,采用高能球磨法制备Cu-Mn合金粉末,研究烧结温度为650~850℃、Mn含量(质量分数)为10%~50%的Cu-Mn合金的烧结性能。结果表明:随Mn含量增加,Cu-Mn合金的相对密度和抗拉强度先增大后减小,但Mn含量过高时生成较多的Mn O,导致合金性能下降;随烧结温度升高,合金的相对密度和抗拉强度增大。850℃下烧结的67Cu-33Mn合金孔隙较小、组织均匀,其相对密度和抗拉强度均达到最大值,分别为91.62%和610.91 MPa,表明67Cu-33Mn合金具有最佳的烧结活性,宜作为Cu与CuCrZr合金连接的中间层。     

Thermodynamics of dilute bcc Fe-Si alloys

The thermodynamic properties of silicon in the α-phase of the Fe-Si system in the region 0.028 <x _Si < 0.084 and 1100 < °C < 1370 has beem measured by the emf cell Mo, Si(s) | SiO₂-Li₂O | (Si-Fe)(s), Mo. The results are expressed in the form $$\log {\text{ }}\gamma _{Si}^\alpha {\text{ = 1}}{\text{.19 }} - {\text{7070/}}T + [ - 6.30 + 18,300/T]x_{Si} $$      

Internal oxidation of dilute Co-Ti alloys

The kinetics of internal oxidation of Co-Ti alloys and the crystal structures and morphologies of the internal oxide particles have been investigated in the temperature range 900 to 1080°C. Three oxides were observed:δ-TiO, TiO₂ (rutile) and CoTiO₃. The permeabilities of oxygen in Co were calculated from the observed internal oxidation kinetics using an analysis due to Meijering as well as an analysis based on a more rigorous solution of the diffusion equations. The factors affecting the size and morphology of internal oxide particles are discussed.     

Solidification of undercooled dilute tin-lead alloys

The rate of solidification of dilute tin-lead alloys has been measured as a function of the initial undercooling (up to 45°C) and the solute content (up to 2 wt pct lead). Solidified specimens were examined by metallography and X-ray diffraction to obtain information on the solidification process and the resulting grain structure. Over an intermediate range of undercoolings, it was found that dendrites grow in the tin-lead alloys as much as four times faster than in pure tin at the same undercooling. This result is inconsistent with any present theories for dendrite growth kinetics in binary alloys. At both lower and higher undercoolings there is no evidence for growth by simple extension of dendrites along the specimen, and solidification rate measurements made under these conditions are probably not indicative of normal dendrite growth kinetics. A. W. Urquhart and G. L. F. Powell were formerly at the Thayer School of Engineering.     

Internal oxidation of dilute Cu-Ti alloys

Metallurgical and Materials Transactions A - The kinetics of internal oxidation of dilute Cu-Ti solid solutions, containing up to 1 wt pct Ti have been investigated over the temperature range 700...     

Internal oxidation of dilute Cu-Ti alloys

The kinetics of internal oxidation of dilute Cu-Ti solid solutions, containing up to 1 wt pct Ti have been investigated over the temperature range 700 to 900°C, and the oxide morphologies produced have been studied by electron metallography. Values of the solubility-diffusivity products for oxygen in copper (N_o ^(s)D_o) are in good agreement with those obtained for pure copper by electrochemical techniques. The TiO₂ particles formed in the Cu-matrix are extremely small (50-200?) and appear to be ellipsoidal in shape. The oxide particle size has been observed to increase linearly with distance below the specimen surface. In addition, electron metallography reveals TiO₂ particles both in the matrix and at grain boundaries which exhibit interesting fringe contrast or “stripes” which are perpendicular to the major axis of the ellipsoids. The origin and possible significance of these regions in terms of coherency of the TiO₂/Cu interfaces are discussed. The interfacial energies for incoherent TiO₂ /Cu interfaces have been found to be quite low, on the order of 400 to 700 ergs/cm². D. ADAMONIS is formerly Graduate Student Assistant     

Internal oxidation of dilute Co-Ti alloys

The kinetics of internal oxidation of Co-Ti alloys and the crystal structures and morphologies of the internal oxide particles have been investigated in the temperature range 900 to 1080°C. Three oxides were observed:δ-TiO, TiO₂ (rutile) and CoTiO₃. The permeabilities of oxygen in Co were calculated from the observed internal oxidation kinetics using an analysis due to Meijering as well as an analysis based on a more rigorous solution of the diffusion equations. The factors affecting the size and morphology of internal oxide particles are discussed. Formerly graduate student assistant, Department of Metallurgical and Materials Engineering, University of Pittsburgh, Pittsburgh, PA 15261 This paper is based, in part, on a thesis submitted by J. Megusar in partial fulfillment of the requirements for the Ph.D. Degree, University of Pittsburgh, April, 1974.     

Thermoelectric properties of dilute PbTe-GeTe alloys

Stablen-type alloys significantly superior to PbTe over the temperature range 300° to 800°K have not yet been reported. While in many cases alloying of PbTe with other materials lowered its thermal conductivity, the degradation of the electrical properties more than offset this gain. A study will be described indicating that the figure-of-merit in an alloy system can reach a maximum at low alloy concentrations (<15 pct) rather than at high concentrations by maximizing the difference in atomic mass and lattice parameter of the two alloying materials. This concept led to the selection of the PbTe-GeTe system for investigation. Experimental results in this system will be compared to theoretical predictions and evaluated. Results will be discussed of optimization of both alloy composition and doping, and of the preparation ofn-type alloys with a figure-of-merit roughly 40 pct greater than PbTe in the range 300° to 800°K. The solubility ofp-type dopants were found to decrease on alloying such that carrier concentrations required for high temperature operation could not be achieved.