On the basis of the dependence of strain-rate sensitivity due to the impurities on temperature at 100 to 200 K, it was found out that the interaction between a dislocation and the impurity in KCl:Sr2+ single crystals could be approximated to the Fleischer’s model taking account of the Friedel relation. The strain-rate sensitivity due to impurities was obtained from the relative curve of strain-rate sensitivity and stress decrement due to oscillation.
                                 
                                
                                        strain-rate sensitivity due to impurities
                                        dislocation
                                        relative curve of strain-rate sensitivity and stress decrement