The Influence of Homogenisation Parameters on the Microstructure and Hardness of AlMnFeMgSi(Zr) Wrought Alloys

Abstract

The purpose of this investigation is to improve the mechanical properties of AlMnFeMgSi wrought alloys by forming a high number density of nano-scaled strengthening dispersoids during homogenisation annealing. The process chain for AlMnFeMgSi wrought alloys includes homogenisation annealing after continuous casting. In this step, inhomogeneities and segregations are dissolved and dispersoids are precipitated. The formed dispersoids hinder grain growth, but usually cannot increase the strength due to their coarse size of some 100 nm. Lower homogenisation temperatures should result in the precipitation of smaller dispersoids during homogenisation. The addition of Zr was investigated to increase this effect. Zr should form further dispersoids from the Al3Zr phase. This requires a fundamental understanding of the temperature-dependent kinetics and the nature of precipitation formation during homogenisation. For this purpose, the as-cast state is first characterised via differential scanning calorimetry. Subsequently, a large number of homogenisation parameters are investigated and quantified via hardness testing. The micro- and nanostructure are investigated for promising parameters and a particle analysis is performed. In the present study, it was possible to precipitate fine dispersoids of few 10 nm by reducing the homogenisation temperature, which resulted in a significant increase in hardness. Alloying with Zr enabled the precipitation of further dispersoids with a size of a few nm in a high number density, which further increased the strength.

Coupling Effect of Mn Addition and Deformation on Mechanical and Electrical Properties of Al-Zr Alloys

“…The TEM examinations were performed on a JEOL-2100 microscope (JEOL Ltd., Tokyo, Japan) operating at 200 kV. The TEM foils were prepared following the standard electro-polishing techniques for Al alloys [16,17]. Cross-sectional TEM examinations were carried out to measure average grain size (d) of the hot-deformed alloys using a linear intercept method, for which at least 150 grains were examined to obtain an average value.…”

“…Similarly, at least 200 precipitates were measured to determine the average inter-particle spacing. More details about the measurements of precipitates are provided in previous publications [16,17,20]. Image analysis was performed by geometrical phase analysis (GPA) [21], where the reference area used in the digital processing as a strain-free area was chosen in the matrix as far as possible from the precipitate under study, as a general procedure.…”

High-Temperature Mechanical Properties and Microstructure of Ultrathin 3003mod Aluminum Alloy Fins

“…On the one hand, good mechanical and sagging resistance properties could be obtained through the optimization of the processing technology. Broer [4] revealed that the mechanical properties resulting from homogenization at lower temperatures could show an increase of approximately 40% compared to the reference homogenization at 550 • C. Kang [9] studied the effects of annealing and deformation on the sagging resistance of 4433/3003/6111/3003 clad sheet, and the results show that low-temperature annealing and a small amount of coarse recrystallized grains could suppress the erosion of Si, resulting in better sagging resistance and strength. On the other hand, alloying to produce dispersed and high-temperature-resistant fine particles is also an effective method to improve high-temperature strengths [11][12][13]26].…”

“…Fin materials usually include a steel strip, a copper strip, and an aluminum strip. Due to its characteristics of light weight, suitable strength, good corrosion resistance, thermal conductivity, brazing and processing formability, 3××× series aluminum alloy has become the main fin material for heat exchangers [1][2][3][4].…”