Positron lifetime measurements as a non-destructive technique to monitor fatigue damage

Technical Report · Mon Sep 01 04:00:00 EDT 1975

DOI:https://doi.org/10.2172/4142050· OSTI ID:4142050

Byrne, J G

In the fatigue cycling of initially hard copper, self consistent positron lifetime and x-ray particle size measurements followed the softening process and revealed a new feature which may be the final development of microvoids before fracture. In the cyclic fatigue of initially soft 4340 steel closely spaced concurrent measurements of these parameters are now in progress. For initially hard 4340 steel fatigue softening was revealed with a large positron lifetime decrease. In hydrogen embrittlement studies positron lifetime was found to be sensitive to hydrogen in an interesting way, i.e., if a specimen is already at its maximum defect density, hydrogen is trapped at some of the defects, reduce their attraction for positrons and hence cause a decrease in positron lifetime; conversely in a soft specimen, hydrogen generates more dislocation length than it can trap at (thus cancelling) hence a positron lifetime increase occurs. In electron irradiated and annealed single crystal copper 4 annealing peaks were seen at 125, 270, 400, and 650$sup 0$K. A clear correlation between decreasing positron lifetime and increasing percent porosity in $alpha$ alumina was established. This behavior is quite the opposite to that in metals. (auth)

• Research Organization: Utah Univ., Salt Lake City (USA). Div. of Materials Science and Engineering
• DOE Contract Number: E(11-1)-2128
• NSA Number: NSA-33-001241
• OSTI ID: 4142050
• Report Number(s): COO--2128-11; UTEC--75-130
• Country of Publication: United States
• Language: English

Related Subjects

*ALUMINIUM OXIDES-- POROSITY
*COPPER-- PHYSICAL RADIATION EFFECTS
*POSITRONS-- LIFETIME
*STEELS-- FATIGUE
360103* --Materials--Metals & Alloys--Mechanical Properties
ANNIHILATION
HARDNESS
HIGH TEMPERATURE
HOT PRESSING
HYDRIDES
LOW TEMPERATURE
MEDIUM TEMPERATURE
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
NONDESTRUCTIVE TESTING
ROCKWELL HARDNESS
SINTERED MATERIALS
TEMPERATURE DEPENDENCE