Strengthening mechanisms in Elgiloy

The effects of cold-working and age-hardening on the microstructure of Elgiloy (composition in wt %, 40 Co, 20 Cr, 15 Ni, 7 Mo, 2 Mn, 0.1 C, balance Fe) have been established. 36% and 72% cold reduction of the solution treated (ST) alloy (f c c) produced a network of thin f c c deformation twins and h c p-martensite platelets. The subsequent age-hardening of the cold-worked strip noted at 500° C was attributed to the formation of additional e-phase (via the _{f c c h c p} transformation), whereas the ST condition did not harden significantly at this temperature. In contrast, ageing the ST condition at 800° C for periods >1000 h caused an increase in hardness due to the formation of a coarse Mo-Co-Cr intermetallic compound together with a smaller amount of M₂₃C₆ carbide, while age softening of the cold-worked strip occurred at this temperature as a result of recovery and dissolution of the deformation induced-phase.     

Three-dimensional simulation of time-coded emission tomography

In this paper we discuss the potentialities of a time-coded single photon emissive imaging system for thyroid tomography. We have performed three-dimensional simulation studies in order to answer two questions: 1) does this coded aperture device produce good quality reconstructions, and 2) can the reconstruction be carried out sufficiently fast on a microcomputer. Our study leads to the conclusion that both questions can be answered affirmatively. Hence, time-coded emission tomography is a potentially useful imaging technique for diagnostic clinical practice.