双相不锈钢瞬时液相连接接头的组织结构及等温凝固模拟
Joint microstructure and isothermal solidification modeling during transient liquid-phase bonding of a duplex stainless steel
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摘要: 采用镍基非晶态合金作中间层,对双相不锈钢进行了瞬间液相连接试验研究.利用场发射扫描电镜(FE-SEM)对连接接头组织进行了观察;利用能谱仪(EDS)和波谱仪(WDS)对接头处微区成分进行了分析,使用X射线衍射仪对连接接头物相组成进行了确定.结果表明,在等温凝固完成前,在中间层和基材的结合处第二相析出物主要是BN,在中间层区域主要物相是γ-Ni固溶体,Ni3B和Cr-borides.此外采用三种扩散模型对等温凝固完成时间进行了计算,对比试验结果,溶质分布模型所得数值更接近真实值,更适合该连接过程.Abstract: An experimental investigation on transient liquid-phase bonding of a duplex stainless steel was carried by using Ni-based amorphous alloy as the interlayer.The microstructure of the bonded joint was observed with field emission scanning electron microscope(FE-SEM).The chemical compositions were analyzed by energy-dispersive X-ray spectroscopy(EDS) and wavelength-dispersive spectrometry(WDS).Phase structure of the bonded joint was identified by using X-ray diffraction(XRD).The results indicated that before the completion of isothermal solidification, the major secondary-phase precipitate present in the interface region between the insert and base alloy was BN.The dominating phases appeared in the interlayer zone were γ-Ni solid solution, Ni3B and Cr-borides.Additionally, three diffusion models were employed to calculate the completion time of the isothermal solidification.By contrast to experimental results, the value obtained by solute distribution model was close to the actual value, and this model was considered to be suitable to the bonding process.