Musina E. A., Kalinina N. E., Tymoshenko Zh. I.
Oles Honchar Dnipropetrovsk National University
THE INCREASE OF MECHANICAL PROPERTIES OF THE POWDERY ALLOY AK6 THAT CONTAINS NANO-COMPOSITIONS
For aircraft apparatus materials with low specific weight and high durability are necessary. These materials include the deformed aluminum alloys.
Alloy AК6 refers to aluminium alloys deformed system Al-Cu-Mg and is intended for complex components and the average strength, the manufacture of which requires high plasticity in a hot condition.
To improve the properties of the material, it was suggested to combine the object of strength AК8 and plasticity AК6 in one material. To overcome shortcomings inherent in the production of materials from cast alloy, a new process has been developed, which is in forging the details of sintered powder blanks.
The alloy AК6, is taken as a base and it is additionally alloyed with iron (up 1.5 %). Powder technologies make it possible to transform harmful impurity (Fe) in useful alloying element. To improve the mechanical properties of the alloy powder composition nanodisperse powder SiC average size of 100nm was put.
The research of microstructure determins that the structure of the alloy AK6 after heat treatment consists of grains of solid solution on the basis of aluminium and inclusions intermetallic connections СuА12 and Мg2Sі. Comparative analysis of serena structure shows that the thermal treatment of structural anisotropy significantly decreased.
The microstructure of alloy powder on the contrary has significantly smaller grain size, and is characterized by the absence of anisotropy, higher density. Comparative analysis illustrates the advantage of the powder alloy cast over. Increased dispersion of intermetallic particles evenly distributed in aluminum matrix that provides a higher hardness, strength, toughness.
The increase in the uniformity of the structure of the alloy AK6 was achieved by using thermally hardening treatment. The temperature of heating for hardening was selected on the basis of state diagrams of the systems of Al-Cu, which is equal to 450°С. At this temperature, the formation of phases of intermetallic FeAl3, FeAl2. Occur after quenching artificial getting old has been done at the temperature of 160°C for 4 hours.
Homogeneous dispersed structure of powder alloy after heat treatment has improved mechanical properties, unlike cast status. So, the tensile strength increased from 447 to 475 MPa, yield strength – from 378 to 387 MPa, at almost constant plastic properties.