Rečnik Simon, Vončina Maja, Nagode Aleš, Medved Jožef
Impol 2000, d. d., Partizanska 38, SI-2310 Slovenska Bistrica, Slovenia.
Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva Cesta 12, SI-1000 Ljubljana, Slovenia.
Materials (Basel). 2023 Sep 16;16(18):6241. doi: 10.3390/ma16186241.
The present study comprises an investigation involving thermodynamic analysis, microstructural characterisation, and a comparative examination of the solidification sequence in two different aluminium alloys: EN AW 6026 and EN AW 1370. These alloys were modified through the addition of pure indium and a master alloy consisting of indium and bismuth. The aim of this experiment was to evaluate the potential suitability of indium, either alone or in combination with bismuth, as a substitute for toxic lead in free-machining aluminium alloys. Thermodynamic analysis was carried out using Thermo-Calc TCAL-6 software, supplemented by differential scanning calorimetry (DSC) experiments. The microstructure of these modified alloys was characterised using SEM-EDS analysis. The results provide valuable insights into the formation of different phases and eutectics within the alloys studied. The results represent an important contribution to the development of innovative, lead-free aluminium alloys suitable for machining processes, especially for use in automatic CNC cutting machines. One of the most important findings of this research is the promising suitability of indium as a viable alternative to lead. This potential stems from indium's ability to avoid interactions with other alloying elements and its tendency to solidify as homogeneously distributed particles with a low melting point. In contrast, the addition of bismuth does not improve the machinability of magnesium-containing aluminium alloys. This is primarily due to their interaction, which leads to the formation of the MgBi phase, which solidifies as a eutectic with a high melting point. Consequently, the presence of bismuth appears to have a detrimental effect on the machining properties of the alloy when magnesium is present in the composition.
本研究包括一项调查，涉及热力学分析、微观结构表征，以及对两种不同铝合金（EN AW 6026和EN AW 1370）凝固顺序的对比研究。通过添加纯铟和一种由铟与铋组成的中间合金对这些合金进行了改性。本实验的目的是评估铟单独或与铋组合作为易切削铝合金中有毒铅的替代品的潜在适用性。使用Thermo-Calc TCAL-6软件进行热力学分析，并辅以差示扫描量热法（DSC）实验。使用扫描电子显微镜-能谱分析（SEM-EDS分析）对这些改性合金的微观结构进行了表征。结果为所研究合金中不同相和共晶的形成提供了有价值的见解。这些结果对开发适用于加工工艺，特别是用于自动数控切割机的创新型无铅铝合金做出了重要贡献。本研究最重要的发现之一是铟作为铅的可行替代品具有很大的适用性。这种潜力源于铟避免与其他合金元素相互作用的能力，以及其以低熔点均匀分布颗粒形式凝固的倾向。相比之下，添加铋并没有改善含镁铝合金的可加工性。这主要是由于它们之间的相互作用，导致形成了MgBi相，该相以高熔点共晶形式凝固。因此，当合金成分中存在镁时，铋的存在似乎对合金的加工性能有不利影响。
