Structure and Properties of Ni₃Al Intermetallic under Vacuum Impact Sintering

Abstract

The compaction, structure, and mechanical properties of intermetallic Ni₃Al corresponding to PN85Yu15 commercial powder, mainly consisting of 50–100 µm particles, are studied. The preforms were impact sintered in 0.013 Pa vacuum at 1100, 1150, 1200, 1250, and 1300 °С. Isothermal holding at these temperatures lasted for 20 min. The samples were compacted at an impact energy of 1200 J/cm³ and an initial impact velocity of 6.5 m/sec. The disk samples were used to cut out rectangular bars to determine their density, resistivity, bending, tensile, and compression strength, conditional fracture toughness, and fracture energy (for notched samples). The Vickers hardness and plasticity of the samples in different types of tests were evaluated. The mechanical properties of Ni₃Al intermetallic powder samples compacted at 1250 °С and above are consistent with those of the standard conventionally melted intermetallic. In particular, the average bending strength is 650–675 MPa, tensile strength 385–400 MPa, fracture toughness 14.6–18.2 MPa • m^1/2, compression strength 1650 MPa, and Vickers hardness 2500–2600 MPa.