Abstract
We considered the possibility of using AlMg10, AlCu5, AlCu5Cd, AlSi12, and AlSi7Zn9 as initial alloys for in situ composites production via oxygen blowing of hydrogen pre-saturated melts as an alternative to AlSi7Fe. The production process provides the destruction of the oxide film on the melt surface. It was demonstrated that oxide film on AlMg10 alloy did not get destroyed due to the heavy thickness because of the porous structure that contributed to its kinetically based growth. Copper-bearing alloys AlCu5 and AlCu5Cd were characterized by the low-strength oxide film and got destroyed before floating, causing the oxide porosity. Silicon-bearing alloys AlSi12 and AlSi7Zn9 provide the dense structure, which makes it clear that to understand the Pilling–Bedworth ratio for basic alloying elements is required for a non-destructed oxide void floating and shall exceed the range of 1.64–1.77. However, the oxide film in silicon-bearing alloys under investigation did not get destroyed into fine particles. AlSi7Zn9 alloy had inclusions of smaller sizes as compared to AlSi12 alloy due to the ZnO that embrittled the film, but which were grouped to form oxide islands. Moreover, zinc was evaporated during blowing. The mechanical properties of the produced composites were based on the alloys under investigation which were in line with their structures. A higher value of the Pilling–Bedworth ratio of impurities was required for fine crushing: The conventionally used AlSi7Fe alloy met this requirement and was therefore considered to be the optimum version.
Highlights
In situ composite material production processes are deemed to be the most costeffective methods that offer prospects for a wider scope of application as compared to ex situ composites [1]
Due to the oxide high density related to the matrix metal, the oxide film on the Al–Mg system alloys with a magnesium content exceeding 3% was well permeable to oxygen
The technology of composite material production implies the destruction of oxide bubbles on the surface of a melt
Summary
In situ composite material production processes are deemed to be the most costeffective methods that offer prospects for a wider scope of application as compared to ex situ composites [1]. The mechanism of the composite material production implies the destruction of oxide bubbles on the surface of a melt [3]; the requirement for an oxide film of sufficient strength needs to be met to avoid premature destruction within the melt volume, on the one hand, and the film needs to contain stress concentrators to ensure film destruction on the melt surface into finest possible fragments, on the other hand. The mechanisms for composite material formation [3] and its properties [3,4,5] were studied using AlSi7Fe alloy. Such a composition is considered to be the most common aluminum secondary alloy that is not characterized by a high strength and is widely used for the production of non-critical parts. The resulting composite material allows increasing the strength of the initial alloy
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