EFFECT OF CR AND ZR ADDITION ON MICROSTRU CTURE AND MECHANICAL-PROPERTIES OF AL-3FE-3NI P M ALLOYS/

The effects of Cr and Zr contents on the mechanical properties of the extrusions from the Al-3Fe-3Ni-x mass%Cr (x=0, 3.0, 4.5) and Al-3Fe-3N i-3Cr-x mass%Zr (x=0, 0.7, 1.5) alloy powders have been investigated a t the temperatures from ambient temperature to 573 K. The microstructu res of these alloy powders and extrusions were analyzed by using an X- ray diffractometer, a differential scanning calorimeter, a scanning el ectron microscope and a transmission electron microscope. The addition of Cr increased the tensile strength of the extrusions and decreased the ductility at all testing temperatures. The low ductility is recove red by the addition of up to 0.7 mass%Zr which increases the strength at the same time. In the alloy containing Cr, the quasicrystalline Al- 80 Cr13.5Fe6.5 phase particles were observed in the rapidly solidified fine powders. The EDX analysis revealed that the quasicrystalline pha se contains the Ni element. After the extrusion at 623 K, the quasicry stalline phase as well as equilibrium Al13Cr2 were finely dispersed in a matrix of the Cr containing alloy, which improved the tensile stren gth at elevated temperatures. In addition, Zr addition to the alloy ca used the finer microstructure and the higher ductility even though it remained in the solid solution.