Dislocation induced strain glass in Ti50Ni45Fe5 alloy

Abstract

Short-range strain-ordered strain glass (STG) appears when the kinetic limitation (local stress field produced by random defects) is strong enough to suppress thermodynamic driven long-range strain-ordered martensitic transition. The point defects and precipitates have been proven to be effective to suppress the martensitic transition and trap the system in a frozen STG state. The dislocations can also introduce the random stress field down to atomic scale, however the effectiveness of which on the crossover from martensite to STG transition remains unknown. Here we report the first experimental finding of the dislocation induced STG transition in a Ti50Ni45Fe5 martensitic alloy when the sample was cold compressed by over 20% plastically. Being different from the point defects and precipitates, the dislocations do not change the chemical composition of the matrix and consequently do not vary the transition temperature too much. Our finding verifies the effectiveness of local randomness on the crossover from martensite to STG transition and suggests that the global effect of defects is not a necessary condition for the occurrence of STG. The present finding may promote the application of STG alloy by assisting on the tuning of functional temperature range in STG alloy through adding the randomness of dislocations.