Mechanical Properties of Composite Rods Produced by Hot Gas Extrusion of the Nickel and Aluminum Powder Mixtures in a Steel Shell

This paper presents the effect of hot gas extrusion (HGE) parameters on the phase composition and mechanical properties of composite rods composed of a core with reaction products of a Ni-Al powder mixture and a steel shell at room temperature. Composite rods are produced in three HGE modes depending on the initial extrusion temperature and the gas pressure in the chamber with parent materials. The phase composition of the produced materials is studied. It is found that the extent of the reaction of the powder mixture increases at higher temperatures of the initial HGE and, accordingly, low gas pressures, but unreacted nickel and aluminum particles remain at the lowest temperature of the initial HGE (at a higher gas pressure). Three-point bending tests show that the yield strength of the composite rod whose core contains plastic inclusions of the parent nickel and aluminum is higher than the yield strength of the steel rod. The rods with the maximum extent of the reaction are observed to have the highest microhardness.