This reference is dedicated to the problem of time-temperature stability of amorphous (non-crystalline) metal alloys with strongly nonequilibrium structure and unique physical and mechanical properties that are obtained by quenching from the melt at a rate that exceeds one millions of degrees c.o.s. second. As a stability test, the behavior of the plasticity of amorphous alloys is studied. The book examines the fundamental characteristics of amorphous alloys, the basic laws of structural relaxation, generalized information about the phenomenon of the ductile-brittle transition (temper embrittlement), the development of physically justified methods of predicting the stability of the properties, and provides information about the attempts of controlling the structure for the purpose of suppressing or deceleration of the ductile-brittle transition and, as a consequence, increasing the temperature and temporal stability of the amorphous state. The book will be useful to students, postgraduate students and researchers who are interested in creating new advanced materials and methods of expanding the temperature and time interval of their practical use.