Process for making chromium alloys of dispersion-modified iron-group metals,and product

Abstract

Abstract DIFFICULTIES IN OBTAINING A UNIFORM PRODUCT HAVE HITHERTO BEEN ENCOUNTERED WHEN MAKING, BY POWDER-BLENDING POWDER-METALLURGY PROCESSES, ALLOYS HAVING AS METAL CONSTITUENTS, BY WEIGHT, AT LEAST 50% OF AN IRON-GROUP METAL AND 10 TO 35% OF CHROMIUM AND OPTIONALLY, LESSER AMOUNTS OF OTHER METALS, SAID ALLOYS BEING DISPERSIONSTRENGTHENED WITH PARTICIES OF A VERY REFRACTORY METAL OXIDE SUCH AS THORIA. THESE DIFFICULTIES ARE NOW OVERCOME BY (1) USING A CHROMIUM POWDER IN WHICH AT LEAST 95% OF THE PARTICLES HAVE A SIZE SMALLER THAN 20 MICRONS, (2) USING AS THE POWDER CONTAINING THE IRON-GROUP METAL A POWDER IN WHICH THE PARTICULATE REFRACTORY OXIDE DISPERSION-STRENGTHENING AGENT IS DISPERSED AS PARTICLES HAVING A NUMBER AVERAGE PARTICLE SIZE IN THE 3 TO 50 MILLIMICRON RANGE, AND (3) MILLING THE POWDER BLEND, PREFERABLY IN A LIQUID MEDIUM IN AN ATTRITION MILL, UNTIL AT LEAST 95% OF THE POWDER PARTICLES HAVE A SIZE LESS THAN 5 MICRONS. OPTIONALLY, THERE IS DISTRIBUTED IN THE MILLED POWDER A SUFFICIENT AMOUNT OF CARBONACEOUS MATERIAL TO REDUCE ANY METAL OXIDE OCCULSIONS, OTHER THAN THE REFRACTORY OXIDE DISPERSION-STRENGTHENING AGENT, UPON TREATMENT WITH DRY HYDROGEN AT ELEVATED TEMPERATURES.

Inventors

• 👤 John B Lambert
• 👤 Harold G Marsh

Bibliographic Details