Accession Number : AD0733677

Title :   Microstructure and Strength Properties of Unidirectionally Solidified Cobalt-Niobium Eutectic Alloy,

Corporate Author : NAVAL SHIP RESEARCH AND DEVELOPMENT LAB ANNAPOLIS MD

Personal Author(s) : Gudas,John P.

Report Date : NOV 1971

Pagination or Media Count : 77

Abstract : The room temperature mechanical properties of unidirectionally solidified Co-Co3Nb eutectic alloy have been studied. Solidification rates varying from 0.000128 cm/sec to 0.001764 cm/sec were employed in producing various microstructures. A well defined lamellar microstructure is produced at rates below 0.000317 cm/sec, while above this rate a lamellar-dendritic structure exists. Room temperature compression and hardness tests indicated increased strengthening with increasing solidification rate as well as verification of a Hall-Petch dependence of fracture stress and hardness upon interphase spacing. Brittle fracture in both types of structure was seen to be initiated by slip in the ductile Co3Nb phase and promoted by crack propagation in the brittle alpha-cobalt solid solution phase. (Author)

Descriptors :   (*COBALT ALLOYS, MECHANICAL PROPERTIES), COMPOSITE MATERIALS, NIOBIUM ALLOYS, EUTECTICS, MICROSTRUCTURE, FRACTOGRAPHY, THESES

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE