Abstract
High-pressure die-cast AlSi10MnMg (AA365) alloys have been used as a material for automotive components exposed to high temperature and corrosive environments. This work determines the correlation of corrosion resistance with the intermetallic compounds and micro-voids of crept AA365 alloys under temperatures ranging from 373 K to 573 K with various applied stresses. The results showed that crept AA365 alloy at 473 K possessed a large amount of the intermetallic phases, compared with crept AA365 alloys at 373 K and 573 K due to the non-equilibrium solute atoms in Al matrix. By contrast, crept AA365 alloy at 573 K contained the lowest number of intermetallic precipitates owing to the remelting of the phases. With regard to the corrosion behavior, the corrosion potentials showed −687.0, −684.0, and −673.0 mVSCE of crept AA365 alloys at 373 K, 473 K, and 573 K, respectively, which means the corrosion occurred slowly on the crept AA365 alloy at 573 K, rather than at 373 K, 473 K. The value of the corrosion current density (Icorr) in the crept HPDC AA365 alloy at 473 K has the highest corrosion current density of 13.3 × 10−6 Acm−2, compared with others. It can be inferred that the high amount of intermetallic compounds gave rise to severe corrosion and led to the harmful micro-galvanic corrosion of crept AA365 alloy, rather than the micro-voids.
Highlights
Due to problems with the regulation of environments and fuel efficiency, it is necessarily required to use lightweight materials in various industries, such as automotive, marine, and aerospace fields
To examine this characteristic of the alloys, this study revealed the correlation between the corrosion resistance and the microstructures, notably intermetallic compounds and micro-voids, of crept AA365 alloys affected by various temperatures and stresses
As temperature increased, the presence of porosities raised relatively. This is because, with the increase in temperature, micro-voids were diffused, growing the size of the voids up [2]. When it comes to the density of the intermetallic compounds, crept AA365 alloy at 473 K shown in Figure 1b has a large amount of the intermetallic phases [15]
Summary
Due to problems with the regulation of environments and fuel efficiency, it is necessarily required to use lightweight materials in various industries, such as automotive, marine, and aerospace fields Under such circumstances, aluminum alloy has been given attention by many industries owing to the significant advantages of lighter weight, excellent corrosion resistance, and high-strength stiffness to weight ratio [1]. AlSi10MnMg (Silafont-36, AA365) alloy is the first successful aluminum–silicon alloy of low iron content and has many benefits, such as good castability, excellent wear, and corrosion resistance, and high elongation [2] This alloy has been primarily produced by the high-pressure die-casting (HPDC) process, which has contributed to high productivity and capability to produce complicated components [3,4]. The HPDC process can give rise to many defects, such as micro-voids and trapped gas, and the defects can provoke the inferior performance of the alloy parts by propagating cracks [2,5,6,7]
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