Phase composition of deformable D16 and B95 aluminium alloys with the quantitative assessment of overburning of different stages of development

Abstract

This paper covers new overburning monitoring methods for D16 and V95 aluminum alloys based on use of a method of an energydispersive X-ray spectral analysis (EDS analysis). It is known that lowered performance of aluminum-based materials is often connected with overburning in their structure. Because the structural changes caused by overburning (flash-off of eutectics and excess low-melting phases and the subsequent crystallization of melted-off microvolumes) are followed by developing porosity, have negative impact on physical and chemical, mechanical and processing properties. The ability to reveal overburning at early stages allows to reject the defective metal. Characteristics sensitive to an early overburning stage are offered based on EDS analysis. A degree of the induced overburning in a D16 sheet is identified. B95 alloy structural components determining the alloy tendency to overburning are revealed. It is found that the EDS analysis makes it possible to reveal changes in the chemical composition of the structural elements of D16 and V95 aluminum alloys and identify an overburning stage quantitatively based on oxygen content. Overburning development leads not only to the higher content of oxygen in the chemical composition of aluminum alloys, but also lowers the electrical conductivity of the material. The paper considers a correlation relationship between the D16 alloy electrical conductivity with overburning induced in it, and oxygen content. The applicability of this method is caused by the method simplicity and a possibility to quantify the defect development in the heat-strengthened deformable aluminum alloys after process heatings. Also this method can be used as an additional research method when metallographic analysis gives no definite answer at identification of early overburning stages.