研究目的
To investigate the modifying effect of the active element Zr on the properties of mechanical alloyed (MA) AgCu28–4.5Ti brazing alloys, especially the joint performance of cubic boron nitride (cBN)/45 steel brazed with AgCu28–4.5Ti–4Zr active brazing alloy.
研究成果
The alloy particles of AgCu28–4.5Ti–4Zr are refined, size is uniform, and the formation of the hard-brittle phase is reduced in the MA process due to the addition of the active element Zr, which is conducive in reducing composition segregation in the laser-brazed layer. The joining mechanism between AgCu28–4.5Ti–4Zr and cBN is due to the formation of a continuous reaction multi-layer between cBN and the brazed alloy containing a sub-outer structure of TiB, TiB2, TiN, ZrB2, and the outer structure consisting of AgZr2, Cu10Zr7. The reaction of the active element Zr with Ag or Cu inhibited the combination of Ti with Ag or Cu under the rapid laser heating and cooling process.
研究不足
The study focuses on the effect of Zr on the properties of AgCu28–4.5Ti brazing alloys and the joint performance of cBN/45 steel brazed with AgCu28–4.5Ti–4Zr active brazing alloys. The limitations include the specific conditions under which the brazing process was carried out and the materials used, which may not be applicable to all brazing scenarios.
1：Experimental Design and Method Selection:
The brazing process was carried out using an Nd:YAG pulsed laser device under a high purity argon atmosphere. The granularity distribution and composition analysis of the MA brazing alloys, microstructural examinations and phase analysis were performed using a laser granularity analyzer, scanning electron microscopy (SEM) equipped with energy dispersion spectrometry (EDS), and X–ray diffraction (XRD) techniques.
2：Sample Selection and Data Sources:
Commercially available cBN and 45 steel were used as the brazing matrix. The surface was ground, polished, and then ultrasonically cleaned with acetone before the brazing test.
3：List of Experimental Equipment and Materials:
An Nd: YAG pulsed laser machine with a lens focal length of 80 mm and spot diameter of 2 mm was employed in the brazing test. The raw elemental powder blends of AgCu28 eutectic and TiH2 and ZrH2 powder were mechanically alloyed in stainless steel grinding media using an all-round planetary ball mill machine.
4：Experimental Procedures and Operational Workflow:
Two kinds of brazing alloys were preloaded on the surface of 45 steel specimens along the brazing direction. The alloys were blended with anhydrous ethanol to avoid the falling of particles. During brazing, the process zone was shielded with Argon atmosphere.
5：Data Analysis Methods:
The results indicate that the alloy particles are refined, sizes are uniform, and the formation of the hard-brittle phase is reduced owing to the addition of the active element Zr. The wettability of the brazing alloy containing Zr is enhanced.
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