Механические свойства композитных стержней, полученных горячей газовой экструзией смеси порошков никеля и алюминия в стальной оболочке

Abstract

The aim of the work is to determine the influence of the hot gas extrusion (HGE) parameters on the phase composition and mechanical properties of composite rods at room temperature consisting of a core with reaction products of a Ni – Al powder mixture and a steel shell. Composite rods were obtained under three different modes of HGE: in the 1st mode, the temperature of the extrusion beginning process (TE) was equal to 730 °С, and the gas pressure (PG) in the chamber with the starting materials was 210 MPa, in the 2nd mode TE — 600 °C, PG — 290 MPa and in the 3rd mode TE — 580 °C, PG — 380 MPa. The numbering of the rods is similar to the HGE modes. The study of mechanical properties was carried out by a three-point bending test and microhardness measurement. The study of the phase composition showed that rod 1 has the greatest completeness of the initial powder mixture reaction. The green nickel and aluminum were found in the core of rod 3. Three-point bending tests have shown that the yield strength of the composite rod will be higher than the yield strength of the steel rod if there are also more plastic inclusions in the core, such as the green nickel and aluminum, as in rod 3. Microhardness measurements have shown that the rods with the greatest completeness of the reaction (rods 1 and 2) have highest average microhardness.