Structure and properties of powder alloys Fe–(45-15)%Ni–(10-5)%Cu, obtained via mechanical alloying

Abstract

The article investigates the structure and properties of Fe–(45-15)%Ni–(10-5)%Cu powder alloys. The production method included low- and high-energy (mechanical alloying, МА) treatment of Fe, Ni, and Cu powders in a planetary ball mills followed by hot-pressing of mixes at 950 °С. After MA, the mixtures consist of composite granules with a lamellar structure and particle size of 10–100 μm. After low-energy treatment, three phases were detected by XRD in hot-pressed samples: α-Fe-based solid solution BCC-(Fe, Ni, Cu), Ni-based solid solution FCC-(Ni, Fe, Cu), and FCC-FeO. The appearance of FeO is caused by the partial oxidation of iron during mixing and hot pressing. The total oxide content does not exceed 1.3 wt%. For Fe-X% Ni-5% Cu alloys the ultimate bending strength depends on the nickel content (X, %) linearly according to the equation σben = −19⋅X + 1995 [MPa], where 15 % ≤ X ≤45 %. Alloys obtained by MA have a homogeneous structure and depending on the composition can be either two- or three-phase. As a result of MA the hardness of the alloys increased by 20–21 HRB, and the ultimate bending strength increases by 300–540 MPa. The alloy with the composition 80%Fe-15%Ni-5%Cu has the maximum bending strength σben = 2135 ± 60 MPa. The wear of MA alloys is (4.1–4.4)⋅10−5 mm3 /(N⋅m) which is more than two times lower than the wear of alloys obtained by low-energy treatment. This work was carried out with financial support from the Russian Science Foundation (Project No. 17-79-20384).