A new indicator of glass-forming ability (GFA) for bulk metallic glasses (BMGs) is proposed based on crystallization processes during cooling and reheating of the supercooled liquid. The interrelationship between this new parameter and the critical cooling rate or critical section thickness is elaborated and discussed in comparison with two other representatives, i.e. reduced glass transition temperature Trg ( =Tg /Tl, where Tg and Tl are the glass transition temperature and liquidus temperature, respectively) and supercooled liquid range △Txg ( =Tx-Tg, where Tx is the onset crystallization temperature and Tg the glass transition temperature). Our results have shown that △Txg alone cannot infer relative GFA for BMGs while the new parameter g, defined as Tx/ (Tg +Tl), has a much better interrelationship with GFA than Trg. An approximation of the critical cooling rate and critical section thickness for glass formation in bulk metallic glasses is also formulated and evaluated. 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.

A family of inexpensive, Al2O3-forming, high–creep strength austenitic stainless steels has been developed. The alloys are based on Fe-20Ni-14Cr-2.5Al weight percent, with strengthening achieved through nanodispersions of NbC. These alloys offer the potential to substantially increase the operating temperatures of structural components and can be used under the aggressive oxidizing conditions encountered in energy-conversion systems. Protective Al2O3 scale formation was achieved with smaller amounts of aluminum in austenitic alloys than previously used, provided that the titanium and vanadium alloying additions frequently used for strengthening were eliminated. The smaller amounts of aluminum permitted stabilization of the austenitic matrix structure and made it possible to obtain excellent creep resistance. Creep-rupture lifetime exceeding 2000 hours at 750°C and 100 megapascals in air, and resistance to oxidation in air with 10% water vapor at 650° and 800°C, were demonstrated.

A new indicator of glass-forming ability (GFA) for bulk metallic glasses (BMGs) is proposed based on crystallization processes during cooling and reheating of the supercooled liquid. The interrelationship between this new parameter and the critical cooling rate or critical section thickness is elaborated and discussed in comparison with two other representatives, i.e. reduced glass transition temperature Trg ( =Tg /Tl, where Tg and Tl are the glass transition temperature and liquidus temperature, respectively) and supercooled liquid range △Txg ( =Tx-Tg, where Tx is the onset crystallization temperature and Tg the glass transition temperature). Our results have shown that △Txg alone cannot infer relative GFA for BMGs while the new parameter g, defined as Tx/ (Tg +Tl), has a much better interrelationship with GFA than Trg. An approximation of the critical cooling rate and critical section thickness for glass formation in bulk metallic glasses is also formulated and evaluated. 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.