Year: 1968
Type: article
Abstract: This program has been designed to evaluate the micromechanical properties related to dimensional stability of several selected structural materials of interest for spacecraft applications.The materials investigated were 2024, 5456, and 6061 aluminum alloys; 1-400 beryllium; TZM molybdenum; A Z 31 magnesium; and Ti-hA1-4V and Ti-5Al-2.5Sntitanium alloys.The program was divided into three topics: evaluation of (1) microyield strength (MYS) a f t e r various heat treatments designed to permit some stress-relief, (2) microcreep properties of some of the heat treated materials a t s t r e s s levels of about 50, 70, and 90 percent of MYS, and (3) thermal and the stress-cycling effects on dimensional stability.The resultant data indicate that both MYS and microcreep properties a r e structure sensitive, but that this sensitivity varies widely among different alloy systems.5456-H34 aluminum showed particularly poor microcreep resistance, exhibiting considerable strain after 1400 hours a t a s t r e s s of only 50 percent of its MYS.TZM-molybdenum, on the other hand, showed essentially no microcreep in 1400 hours a t a s t r e s s of 70 percent of its MYS.Thermal and stress-cycling appeared to cause dimensional changes for mo:t of the alloys examined.Data a r e interpreted in t e r m s of the s t r e s s o r thermal activation of dislocation sources, with dislocation interaction being negligible.
Authors: M. M. Cho, F.C. Holden, R. E. Maringer
Institution: Battelle
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W780333990