This paper reports the results of a systematic investigation into some of the effects of ruthenium additions to WC–Co. The results show that the hardness of WC–Co increases and the toughness ...decreases with increasing the ruthenium content and that ruthenium is a weak inhibitor of WC grain growth. Ruthenium has been found to improve the abrasion resistance of WC–Co on account of the hardening of the binder phase.
Low and high temperature hardness of WC-6 wt%Co alloys Milman, Yu.V.; Chugunova, S.; Goncharuck, V. ...
International journal of refractory metals & hard materials,
1997, 1997-1-00, 19970101, Letnik:
15, Številka:
1
Journal Article
Recenzirano
This paper reports hardness measurements on WC-6 wt%Co of three different grain sizes in the temperature range from −196 to 900 °C. Coarser grades have been found to soften with increasing ...temperature at a higher rate than finer grades. It has been confirmed that hardness decreases with increasing grain size over the whole range of temperatures and it has been shown that the decrease in hardness with increasing grain size follows a Hall-Petch-type relationship at all the temperatures tested.
The Vickers hardness of WC–Co alloys has been measured at temperatures ranging from −196 to 900°C. The cobalt content of the alloys ranged from 10 to 24 vol% and the grain size from 0.5 to 2.3 μm. It ...was found that, at all cobalt contents and all temperatures, the decrease in hardness with increasing grain size can be approximated by a Hall–Petch type relationship. Up to about 600°C the decrease in hardness with increasing temperature appears to be due mostly to the decrease in the intrinsic hardness of the individual phases. Above 600°C the decrease in hardness appears to be due mostly to easier slip transfer across grain boundaries. Finer grained alloys have been found to preserve their hardness at high temperature better than coarser grained alloys, at all cobalt contents.
In traditional software engineering project management, managers provide focused guidance to a team responsible for producing a specific result in a specified amount of time. Today, however, ...organizations are increasingly taking a product line approach to software to exploit product commonalities. Software product line organizations have unique practices and project definitions. These unconventional features offer new challenges and directions for traditional project management. How does the traditional concept of a project - a temporary endeavor aimed at creating a unique product or service - hold up under this new paradigm? In this article, we discuss this question, along with how the idea of a "project" and project management techniques must expand to fit a product line context. In particular, we show how the "overall guidelines, policies, and procedures" that Thayer and Pyster spoke of some years ago remain crucially important in product line organizations today.
The Arcminute Microkelvin Imager Zwart, J. T. L.; Barker, R. W.; Biddulph, P. ...
Monthly notices of the Royal Astronomical Society,
12/2008, Letnik:
391, Številka:
4
Journal Article
Description
This case study describes the overall development of the T-38/F-5 family of fighter/trainer aircraft in terms of configuration development motivation and constraints. Selected systems are ...examined in detail, including the constraints, specifications, and trade-offs that led to important design decisions.
PDF
