Properties Of Yttrium And Rare Earth Metals Oxygen And Alloy Systems. Oxygen And Alloy Systems
Report Number: WADD TR 61-123
Author(s): Love, Bernard
Corporate Author(s): Research Chemicals, Inc.
Laboratory: Directorate of Materials and Processes
Date of Publication: 1961-08
Pages: 198
Contract: AF 33(616)-6829
DoD Project: 7351 - Metallic Materials
DoD Task: 73517
PB Number: PB181115
Identifier: AD0271582
Abstract:
Partial constitutional diagrams were established for a number of systems containing yttrium and the lanthanide elements. These studies were made as the first step in efforts to produce alloys with improved mechanical and atmospheric corrosion properties for use at elevated temperatures. Alpha yttrium and erbium are completely soluble in all proportions. The yttrium-neodymium system is more complex. There is partial solubility at both ends of the system. An intermediate phase is present at the equi-atomic percentage composition. No marked beta phase stabilization was established. The rare earth rich end of the yttrium, erbium, neodymium, and samarium systems with oxygen were investigated. The solubility of oxygen is low in the metals at the temperatures up to the transformation temperature of 1000°C. The transformation temperature of neodymium is essentially unaffected, that of samarium is raised slightly. The nature of the elevated temperature portion of each system is less certain and two alternative phase diagrams are proposed. The preferred diagram indicates the presence of a high temperature interstitial monoxide. The cobalt end of the cobalt-erbium system was investigated. A number of intermetallic compounds are formed. The first of these, Co17Er2, enters into eutectic reaction with cobalt. The solubility of erbium in cobalt is low, and the cobalt phase transformation is essentially unaffected by the presence of small additions of erbium. The cobalt-yttrium system appears to be similar. Tantalum-lanthanum, tantalum-erbium, tantalum-yttrium, niobium-erbium, and niobium-yttrium systems were investigated. All systems were similar in their general characteristics. An extensive liquid immiscibility region is present which terminates in a monotectic very near the tantalum (niobium) end of the system. A eutectic is present at the rare earth end of the system. Room temperature solid solubility is very low, but there may be slight solubility at elevated temperature. The alpha to beta transformation temperature was determined to be 848°C for neodymium, and 930°C for samarium. The transformation temperature of yttrium is approximately 20-30°C below the melting point of yttrium. Both the transformation and melting temperatures are somewhat dependent upon metal purity. Atmospheric corrosion rates were determined in the above systems. Lower rates were found for certain niobium alloys, and for cobalt compositions, with added rare earths. Improved mechanical properties were found for yttrium-erbium alloys and for yttrium-zirconium alloys ascribed to solid solution hardening. The latter age at room temperature, and rapidly overage at elevated temperatures. Procedures for purification of yttrium and erbium by vacuum distillation were developed. Improved methods for oxygen and tantalum analysis are described. The addition of erbium to beryllium yields alloys indicating improved purity and grain refinement.
Provenance: Bombardier/Aero
Author(s): Love, Bernard
Corporate Author(s): Research Chemicals, Inc.
Laboratory: Directorate of Materials and Processes
Date of Publication: 1961-08
Pages: 198
Contract: AF 33(616)-6829
DoD Project: 7351 - Metallic Materials
DoD Task: 73517
PB Number: PB181115
Identifier: AD0271582
Abstract:
Partial constitutional diagrams were established for a number of systems containing yttrium and the lanthanide elements. These studies were made as the first step in efforts to produce alloys with improved mechanical and atmospheric corrosion properties for use at elevated temperatures. Alpha yttrium and erbium are completely soluble in all proportions. The yttrium-neodymium system is more complex. There is partial solubility at both ends of the system. An intermediate phase is present at the equi-atomic percentage composition. No marked beta phase stabilization was established. The rare earth rich end of the yttrium, erbium, neodymium, and samarium systems with oxygen were investigated. The solubility of oxygen is low in the metals at the temperatures up to the transformation temperature of 1000°C. The transformation temperature of neodymium is essentially unaffected, that of samarium is raised slightly. The nature of the elevated temperature portion of each system is less certain and two alternative phase diagrams are proposed. The preferred diagram indicates the presence of a high temperature interstitial monoxide. The cobalt end of the cobalt-erbium system was investigated. A number of intermetallic compounds are formed. The first of these, Co17Er2, enters into eutectic reaction with cobalt. The solubility of erbium in cobalt is low, and the cobalt phase transformation is essentially unaffected by the presence of small additions of erbium. The cobalt-yttrium system appears to be similar. Tantalum-lanthanum, tantalum-erbium, tantalum-yttrium, niobium-erbium, and niobium-yttrium systems were investigated. All systems were similar in their general characteristics. An extensive liquid immiscibility region is present which terminates in a monotectic very near the tantalum (niobium) end of the system. A eutectic is present at the rare earth end of the system. Room temperature solid solubility is very low, but there may be slight solubility at elevated temperature. The alpha to beta transformation temperature was determined to be 848°C for neodymium, and 930°C for samarium. The transformation temperature of yttrium is approximately 20-30°C below the melting point of yttrium. Both the transformation and melting temperatures are somewhat dependent upon metal purity. Atmospheric corrosion rates were determined in the above systems. Lower rates were found for certain niobium alloys, and for cobalt compositions, with added rare earths. Improved mechanical properties were found for yttrium-erbium alloys and for yttrium-zirconium alloys ascribed to solid solution hardening. The latter age at room temperature, and rapidly overage at elevated temperatures. Procedures for purification of yttrium and erbium by vacuum distillation were developed. Improved methods for oxygen and tantalum analysis are described. The addition of erbium to beryllium yields alloys indicating improved purity and grain refinement.
Provenance: Bombardier/Aero