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

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, MA) treatment of Fe, Ni, and Cu powders in a plan-etary ball mills followed by hot-pressing of mixes at 950 degrees C. After MA, the mixtures consist of composite granules with a lamellar structure and particle size of 10-100 mu m. After low-energy treatment, three phases were detected by XRD in hot-pressed samples: alpha-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 sigma(ben) = -19 center dot 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 sigma(ben) = 2135 +/- 60 MPa. The wear of MA alloys is (4.1-4.4)center dot 10(-5) mm(3) /(N center dot m) which is more than two times lower than the wear of alloys obtained by low-energy treatment.