摘要本文选用BNi-2钎料，对TiAl基合金与0Cr18Ni9不锈钢进行真空钎焊，焊后利用扫描电镜、超景深显微镜、显微硬度计等分析了钎焊保温时间和钎焊温度对接头组织与性能以及界面元素扩散的影响。86376

研究结果表明：接头的界面组织明显分为5个反应层。靠近TiAl基合金一侧含有锯齿状灰黑色相的反应层Ⅰ；与Ⅰ层相连的灰色反应层Ⅱ；含有条块状或点状的黑色相的反应层Ⅲ；焊缝中心层Ⅳ；不锈钢母材侧界面反应层Ⅴ。

随着保温时间的延长，TiAl基侧各反应层厚度明显增加，反应层Ⅲ中的黑色化合物相的数量也增多，并且由细小状向粗大状转变；0Cr18Ni9不锈钢侧界面反应区的宽度随保温时间的延长而增大；随着保温时间的延长，钎缝间距呈现减小趋势。

随着钎焊温度的升高，钎缝间距呈现先减小后增大的趋势；钎缝中心区的化合物随着钎焊温度的升高由网状向条状转变，最后只剩断续的块状；TiAl基侧各反应层的硬度值随着钎焊温度的升高而增加，焊缝中心处的硬度值随着钎焊温度的升高而下降，0Cr18Ni9侧界面反应区的硬度值也随着钎焊温度的升高而下降。

毕业论文关键词：TiAl，0Cr18Ni9，BNi-2，钎焊温度，保温时间

Abstract The paper is a study on TiAl/0Cr18Ni9 joint brazed by BNi-2。 After welding, we used scanning electron microscopy, energy spectrum analysis, electron microprobe and micro-hardness tester to analyse the impact of brazing temperature and holding time on microstructure, properties of the joint and the diffusion of the elements at the interface。

The results showed that the interface of the joint could be pided into five reaction layers。 The layer adjacent to the TiAl based alloy contained the jagged black phase was named layer I。 The layer adjacent to layer I with the grey reaction was named layer II。 The reaction layer III contained some lump or punctate black phase。 The layer in the center of weld seam was named layer IV。 The layer side to interface reaction of stainless steel was named layer V。

With the holding time prolonged, the reaction layers’ thickness on TiAl side increased significantly。 The quantities of the black compounds in reaction layer III increased and the shape of them changed from tiny to thick。 The width of the layer on the interfacial reaction zone of 0Cr18Ni9 stainless steel increased with the holding time prolonged and the brazing seam’s spacing decreased。

With the increasing of brazing temperature, the brazing seam’s spacing showed a trend of decreased first and then increased。 The shape of the compounds in the central area of brazing seam changed from mesh to strip。 Finally, only intermittent block left。 The hardness value of layers on TiAl side increased with the increasing of brazing temperature。 And the hardness value of the weld center decreased。 The hardness value of the interfacial reaction zone on 0Cr18Ni9 side also decreased generally。

Keywords：TiAl, 0Cr18Ni9, BNi-2, brazing temperature, holding time

目  录

第一章  绪论 1

1。1 TiAl基合金 1

1。1。1 TiAl基合金特点 1

1。1。2 TiAl基合金的应用 1

1。1。3 TiAl基合金的焊接工艺 1

1。2 不锈钢 2

1。2。1 不锈钢的发展 2

1。2。2 0Cr18Ni9钢 2

1。3 真空钎焊 3

1。3。1 真空钎焊的优缺点 3

1。3。2 真空钎焊钎料的选择