DE2303802

1413762 Dispersion strengthened alloys INTERNATIONAL NICKEL Ltd 24 Jan 1973 [31 Jan 1972] 3554/73 Headings C7A and C7D Mechanically alloyed dispersion strengthened powders of "saturation hardness" formed by dry milling according to Specification 1265343 are hot worked under correlated conditions of temperature, reduction ratio and strain rate to leave residual strain and then zone annealed to form coarse grains elongated in the working direction. Hot working is preferably effected by sheathing the powder in a steel can and extruding at 870- 1200‹C, a reduction ratio of 7-35, and a strain rate above a defined minimum value. The preferred temperature and reduction ratio conditions fall within the area KLMNOK of the Fig. Zone annealing is effected at 1200‹C minimum and the rate of travel of the hot zone may be 25-432 mm./hour. The preferred alloy contains in wt per cent 5-60Cr, 0.5-6.5Al, 0.5-6.5Ti, 0-15Mo, 0-20W, 0-10Nb, 0-10Ta, 0-3V, 0-2Mn, 0-2Si, 0-0.75C, 0-0.1B, 0-1Zr, 0-0.2Mg, 0-6Hf, 0-35Fe up to 10% volume of a refractory dispersoid e.g. TLO 2 , Y 2 O 3 , La 2 O 3 and rare earth oxides, and balance of at least 40 of Ni and/ or Co. The hot worked billet is maintained for a minimum of 5 minutes and preferably above 10 minutes at the grain growth temperature. After annealing the billet is solution treated at 950- 1320‹C for ¢-16 hours and then aged at 620- 870‹C for 1-100 hours.