The Kinetics of Primary Alpha Plate Growth in Titanium Alloys

The kinetics of primary α-Ti colony/Widmanstätten plate growth from the β are examined in Ti-6246, comparing a simple quasi-analytic model to experiment. The plate growth velocity depends sensitively both on the diffusivity D(T) of the rate-limiting species and on the supersaturation around the growing plate. These result in a maxima in growth velocity around 40 K below the transus, once sufficient supersaturation is available to drive the plate growth. In Ti-6246, the plate growth velocity was found to be around 0.32 μm min−1 at 850 °C, which was in good agreement with the model prediction of 0.36 μm min−1. The solute field around the growing plates, and the plate thickness, was found to be quite variable, due to the intergrowth of plates and soft impingement. This solute field was found to extend to up to 30 nm, and the interface concentration in the β was found to be around 6.4 at. pct Mo. It was found that the increasing O content from 500 to 1500 wppm will have minimal effect on the plate lengths expected during continuous cooling; in contrast, Mo approximately doubles the plate lengths obtained for every 2 wt pct Mo reduction. Alloys using V as the β stabilizer instead of Mo are expected to have much faster plate growth kinetics at nominally equivalent V contents. These findings will provide a useful tool for the integrated design of alloys and process routes to achieve tailored microstructures.

It is good to be green

PurposeThis paper aims to discuss how the influence of consumer and investor opinions for green corporate accountability and the creation of new government regulations in favor of protecting the environment have pushed green issues onto the boardroom agenda and onto outsourcing vendors' growing plate of priorities.Design/methodology/approachThe data presented and the opinions discussed in this paper are based on the on‐going research behind The Black Book of Outsourcing, by Douglas Brown and Scott Wilson.FindingsThe paper presents a wealth of data that clearly highlight how environmental issues and the ability to display an environmental‐friendly culture are becoming vital to all outsourcing stakeholders. Also, using the data analysis, it delivers a 13 steps process to develop a green outsourcing initiative.Originality/valueThis paper discusses one of the latest trends in outsourcing, and it does so by providing numerous relevant data. As such, it contributes to setting a relevant research agenda. At the same time, it provides an in‐depth analysis of various industry first‐movers, and based on that it delivers a process that can be used by practitioners to develop green outsourcing offerings.