Accession Number : AD0811907

Title :   RESEARCH ON DISPERSION STRENGTHENED COBALT-BASE ALLOYS.

Descriptive Note : Summary rept. 15 Feb 66-14 Feb 67,

Corporate Author : DU PONT DE NEMOURS (E I) AND CO WILMINGTON DE

Personal Author(s) : Mincher, Albert O.

Report Date : MAR 1967

Pagination or Media Count : 84

Abstract : Cobalt-base alloys strengthened with fine ThO2 dispersions were processed by powder metallurgy techniques to round bar and evaluated for physical and mechanical properties. Alloys were studied with varying levels of Ni (10 to 30%), Cr (10-30%), Fe (20%), ThO2 (1 to 4%), and Zr (0.2%). The Co-10Ni-2ThO2-0.2Zr alloy had the best combination of fabricability and high temperature strength in the non-chromium containing alloys. For 100 hour life in vacuum at 2000 F, rupture strength of 85% swaged bar of this alloy was >16,000 psi in swaged (find grained) bar and 15,000 psi in recrystallized bar. Tensile strength of annealed bar at 1400 F was improved by a molybdenum addition from 39,000 psi in the Co-10Ni-2ThO2-0.2Zr alloy to 104,000 psi in the Co-15Ni-15Mo-4Th02 alloy. High temperature strength of the oxidation-resistant chromium containing alloys increased with increasing grain size and with increasing ThO2 loading. The Co-Ni-Cr-ThO2 compositions gave the best high temperature strengths. In particular, the Co-20Ni-18Cr-4ThO2 alloy had tensile strength of up to 27,000 psi at 2000 F, and rupture strength was 15,000 psi for 100 hour life in air at 2000 F. The Co-20Fe-20Cr-4ThO2 alloy had a tensile strength of 16,400 psi at 2000 F. The Co-Cr-ThO2 alloys all had low tensile strength (<10,000 psi) at 2000 F. (Author)

Descriptors :   *DISPERSION HARDENING), *OXIDES), (*COBALT ALLOYS, (*THORIUM COMPOUNDS, TENSILE PROPERTIES, CORROSION INHIBITION, RECRYSTALLIZATION, RUPTURE, SINTERING, NICKEL ALLOYS, MOLYBDENUM ALLOYS, CHROMIUM ALLOYS, ANNEALING, STRESSES, THERMAL STABILITY, EXTRUSION, POWDER METALS, COMPACTING, GRAIN SIZE, PARTICLE SIZE, ZIRCONIUM ALLOYS, ELECTRON MICROSCOPES, CRYSTAL STRUCTURE.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE