采用真空扩散焊接技术将镁合金(MB2)与铝合金(LY12)的焊接, 采用超声波无损检测、电子探针、X射线衍射和扫描电镜等手段研究了焊接温度对焊接接头界面附近组织结构的影响, 分析了界面反应物的生成机理。结果表明, 随着焊接温度的升高, 焊接界面的焊合率提高, 在焊接压力为3 MPa、保温时间为100 min的条件下, 温度升高到480℃完全焊合, 在Al侧和Mg侧分别形成了Al(ss, Mg)和Mg(ss, Al)固溶体, 焊接界面形成了Al12Mg17、AlMg、Al3Mg2三种金属间化合物层, 其厚度随着焊接温度的升高而增加, 其中AlMg层厚度增长得最快, 接头断裂发生在金属间化合物层且呈阶梯状断裂。界面扩散区的形成主要由有效物理接触阶段、固溶体形成阶段、金属间化合物相形成阶段以及金属间化合物增长阶段组成。
The alkaline-earth metal substituted compounds Y0.95R0.05CoO3 (R=Ca, Sr, Ba) were prepared by sol–gel process, and the effect of substituting on its electrical transport and thermoelectric properties were systematically investigated. The results show that with the increase of Ca2+、Sr2+、Ba2+ ionic radius, the electrical resistivity of the Y0.95R0.05CoO3 compounds increases gradually, Seebeck coefficient was improving, and the power factor decreases, in corresponding temperature range. The high-temperature thermoelectric power factor of the YCoO3 system can be improved effectively by the substitution of Ca2+ with smaller radius approaching that of the ion Y3+.
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