Development of Lightweight Titanium Base Alloys
Abstract
The goal of the program on Development of Lightweight Titanium Base Alloys was to develop new titanium alloys with 10% lower density, 50% higher elastic modulus, and 50% higher strength than Ti-6Al-4V and a 150 deg C increase in service temperature above that of Ti-6Al-2Sn-4Zr-2Mo. The feasibility of adding significant amounts of Be, Li, and Mg to Ti base alloys to effect these improvements was investigated. Rapid solidification processing was employeed to obtain extended solid solutions of Be concentrations far exceeding the limits indicated by the equilibrium phase diagram. This solid solution was expected to provide significant strengthening because of the atomic-radius mismatch between Ti and solute atoms, and to provide dispersion strengthening via fine dispersions. Master alloys of Ti-Al-Be and Ti-V-Al-Be were produced by melting pieces of Lockalloy (60 wt%) Be - 40 wt% Al) and elemental additions in a Beo- wash-coated alumina crucible, and casting at 1450 deg C into a chilled mold. Powder was produced by melting the master alloys in an uncoated graphite crucible, initiating metal flow at 1300 deg C, and dispersing the stream by centrifugal atomization. Target alloy chemistries were obtained, although the powders contained 0.5-0.7 wt% oxygen. This oxygen pickup occurred during casting and is attributed to the BeO wash and/or the relatively poor vacuum. The powders were extruded into 12-cm diameter rods at 900 and 950 deg C (except Ti-34Al-4Be which was extruded at 1150 deg C). Successful extrusions were obtained for Ti- 6Al-4V-4Be, Ti-6Al-4V-7Be, Ti-25V-3Al-4Be, Ti25V-4Al-7Be, and TI34Al-4Be.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1989
- Accession Number
- ADA286162
Entities
People
- D. S. Schwartz
- J. E. Deffeyes
- J. E. O'neal
- R. J. Lederich
- T. C. Peng