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采用X射线、光学显微镜及扫描电镜等手段研究 2 618合金中的组织与相结构 ,并研究了元素钇在 2 618合金中的存在形式及其对合金力学性能的影响。结果表明 ,微量钇元素在铝合金中是以化合物形式存在的 ;钇对合金中的铸态组织及Al9FeNi相形态没有影响。由于微量钇的加入 ,降低了铜与镁在 2 618合金中的固溶量 ,减少了时效析出相Al2 CuMg的数量 ,从而降低 2 618合金的室温强度和在 2 5 0℃的高温瞬时强度 ;但由于微量钇减少了铜与镁在 2 618合金中的扩散速度 ,延缓了时效相的粗化 ,并由于第二相数量的增多 ,因此提高了 2 618合金在2 5 0℃经 10 0h高温热暴露后的高温瞬时强度。
The microstructure and phase structure of 2 618 alloy were investigated by X-ray, optical microscope and scanning electron microscope. The existence of the element yttrium in 2 618 alloy and its effect on the mechanical properties of the alloy were investigated. The results show that a trace amount of yttrium is present as a compound in the aluminum alloy. Yttrium has no effect on the as-cast microstructure and the morphology of the Al9FeNi phase in the alloy. Due to the addition of trace amount of yttrium, the amount of solid solution of copper and magnesium in 2 618 alloy is decreased and the amount of Al 2 CuMg in the precipitated phase is decreased, thereby decreasing the room temperature strength of 2 618 alloy and the high temperature transient strength at 250 ℃. However, the trace amount of yttrium reduced the diffusion rate of copper and magnesium in 2 618 alloy and retarded the coarsening of the aging phase. Due to the increase of the number of the second phase, the number of 2 618 alloy increased by 10 0 h at 250 ℃ Thermal exposure to high temperature instantaneous strength.