Effect of Heat Treatment on Microstructural Evolution and Microhardness Change of Al-5Zn-0.03In-1Er Alloy

• Published in: Metals (Basel ) Vol. 12; no. 3; p. 370
• Main Authors: Cui, Jin, Tang, Zhichao, Yu, Muzhi, Hu, Jiajin, Chen, Xiaoyang, Xu, Zhengbing, Zeng, Jianmin
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.03.2022
• Subjects: Al-Zn-In-Er alloy; Alloying elements; Alloys; Aluminum alloys; Aluminum base alloys; Casting alloys; Dislocations; Efficiency; Electrochemical analysis; Electron microscopy; Energy spectra; Erbium base alloys; Evolution; Grain boundaries; Heat treatment; High temperature; Homogenization; line scanning analysis; Mechanical properties; Microhardness; Microstructure; Nanoparticles; Optical microscopy; Scanning electron microscopy; Solid solutions; Spectrum analysis; ultra-high temperature treatment; Ultrahigh temperature; Zinc; Japan
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met12030370

Adding an appropriate amount of Er element to Al-Zn-In alloys can improve the electrochemical performance of Al alloys; it is convenient to study the electrochemical behavior of the alloy in the rest of our work. However, Er segregation in solid solutions which reduced the comprehensive properties of alloys was difficult to reduce and there was no report on the homogenization of Al-Zn-In alloys. We found that the ultra-high temperature treatment (UHTT) can obviously reduce Er segregation. To explore the better homogenization treatment and the microstructure evolution of Al-5Zn-0.03In-1Er alloy after UHTT, we carried out a series of heat treatments on the alloy and characterized the microstructure of the alloy by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy spectrum analysis (EDS) and transmission electron microscopy (TEM). The results showed that the main element Er of the Al-Zn-In-Er was largely enriched in grain boundaries after UHTT; the distribution Zn and In was almost unchanged. The as-cast Al-Zn-In-Er alloy consisted mainly of α(Al) solid solution and Al3Er phase. As the temperature of UHTT increased and the treatment time prolonged, the precipitated phase dissolved into the matrix, and there were dispersed Al3Er particles in the crystal. The proper UHTT for reducing the interdendritic segregation of the alloy was 615 °C × 32 h, which was properly consistent with the results of the evolution of the statistical amount of interdendritic phase, the line scanning analysis and the microhardness. Moreover, the microhardness of the alloy after treatment of 615 °C × 32 h was obviously higher than that of the as-cast alloy because of the anchoring effect of Al3Er nanoparticles on the movement of dislocations.