Influence of oxygen on performance of multi-principal element alloy as braze filler for Ni-base alloys
Influence of oxygen on performance of multi-principal element alloy as braze filler for Ni-base alloys
复制标题
DOI：
10.1016/j.jmapro.2023.01.017
复制
发表时间：
2023-02
影响因子：
6.2
通讯作者：
B. Schneiderman;A. Hansen;A. Chuang;Zhenzhen Yu
中科院分区：
文献类型：
--
作者：
B. Schneiderman;A. Hansen;A. Chuang;Zhenzhen Yu
在多主元素合金（MPEAs）的制造中，铸造过程通常是将氧引入材料系统的主要点，这通过实验室规模的纽扣电弧熔炼过程来证明。如果单独用作结构材料或在工程应用中使用，例如用作填料材料以使得能够连接通常被认为难以连接的相似或不同的合金对，则氧的引入引起了对这些合金的机械性能的关注。在这项工作中，氧化物夹杂物在铸态非等原子MnFeCoNiCu MPEA和镍基合金与此MPEA钎焊接头进行了评价，通过同步辐射X射线衍射图谱和电子显微镜。MnO被发现是普遍存在于整个铸造MPEA和化学还原钎焊过程中微量铝从基础材料，镍基合金600。MnO与Al的不完全反应，以及与Cr的一些替代反应，在钎焊接头中留下MnO、Al 2 O3和Cr2 O3的混合物，由于定向凝固，氧化物集中在钎焊中心线附近。在钎焊接头中，检测到的非氧化物成分相是FCC基质和Cr23 C6、Cr 7 C3和TiN颗粒，这些都是合金600的原生成分。还评估了在600-800 °C的升高的使用温度下钎焊接头内的氧化物的演变。虽然MnO和Al 2 O3在高温服务期间是稳定的，但Cr2 O3颗粒生长到几百微米，MPEA中的溶解氧为氧化物生长提供了重要来源。比较拉伸性能的钎焊条件与后服务条件表明，氧化物颗粒的演变有助于钎焊接头的强度增加和延性降低。评价颗粒形态之间的断裂表面的个别标本表明，大Cr2 O3颗粒和连续的簇网络的Al 2 O3的功能最有害的总伸长率。因此，在钎焊和使用条件下，含氧物质的完全演化对钎焊接头的延展性是有害的，这突出了在工程应用的MPEAs的初始制造中氧控制的重要性。
In manufacturing of multi-principal element alloys (MPEAs), the casting process is often a primary point of oxygen introduction to the material system, which was demonstrated by the laboratory scale button arc-melting process. Oxygen introduction raises concerns for the mechanical performance of these alloys if employed as structural materials alone or in engineering applications, such as serving as filler materials to enable joining of similar or dissimilar alloy pairs that are conventionally considered difficult to join. In this work, oxide inclusions in an as-cast off-equiatomic MnFeCoNiCu MPEA and Ni-base alloy braze joints made with this MPEA were evaluated by synchrotron x-ray diffraction mapping and electron microscopy. MnO was found to be prevalent throughout the cast MPEA and was chemically reduced during brazing by trace Al from the base material, Ni-base Alloy 600. Incomplete reaction of the MnO with Al, and some alternative reaction with Cr, left a mixture of MnO, Al2O3, and Cr2O3in the as-brazed joint, with the oxides concentrated near the braze centerline due to directional solidification. In the braze joints, the non-oxide constituent phases detected were an FCC matrix and particles of Cr23C6, Cr7C3, and TiN which are all native to Alloy 600. The evolution of oxides within the brazed joints at elevated service temperatures of 600–800 °C was also evaluated. While MnO and Al2O3were stable during high-temperature service, Cr2O3particles grew to several hundred microns, with dissolved oxygen in the MPEA providing a significant source for oxide growth. Comparing tensile performance of the as-brazed condition with post-service conditions showed that the evolution of oxide particles contributed to an increase in strength and decrease in ductility of the brazed joints. Evaluating particle morphologies among fracture surfaces of individual specimens demonstrated that large Cr2O3particles and continuous cluster networks of Al2O3were the features most detrimental to total elongation. Hence, unmitigated evolution of oxygen-containing species during brazing and service conditions is detrimental to the ductility of the brazed joints, which highlights the importance of oxygen control in initial manufacturing of MPEAs for engineering applications.