INFLUENCE OF THE POWDER PARTICLE-SIZE ON TENSILE PROPERTIES OF NI3AL PROCESSED BY RAPID SOLIDIFICATION AND HOT ISOSTATIC PRESSING

The mechanical properties of PM Ni3Al with boron additions as a functi on of the powder particle size have been investigated. The study has b een carried out by tensile tests from room temperature up to 1000 degr ees C. The rapidly solidified powders have been produced by argon atom ization, Cans with different powder particle sizes, < 25 mu m, 25-50 m u m, 50-100 mu m and 100-200 mu m were hipped at 1100 and 1200 degrees C under 150 MPa. The microstructure of the consolidated material cons ists of ordered Ni3Al. The hardness and tensile properties of compacts depend on particle size and the effect is more evident for the low-te mperature range. The material obtained from the smaller size powders e xhibited the best mechanical behaviour. A dependence between tensile p roperties, especially elongation to failure, and the curvature radius of the flat tensile sample has been found. It has been demonstrated th at the use of a small curvature radius gives more representative value s of tensile properties as the deformation is restricted to the gauge length.