GLASS-FORMING ABILITY AND GLASS STABILITY IN SIMPLE SYSTEMS

The interrelationship between glass-forming ability and stability of glass to devitrification is examined. Quantitative criteria for assessing the latter properties are adopted. Glass-forming ability is gauged by the critical cooling rate, R(c), and glass stability by the difference between the temperature of maximum crystallization in a non-isothermal DTA/DSC experiment, T(x), and a standard temperature such as the glass transition temperature, T(g). The variations in R(c) and T(x) - T(g) with parameters which control nucleation and growth rates are examined, and it is shown that the latter quantities can behave quite differently. It is concluded that glass-forming ability and glass stability are independent (albeit related) concepts.