This paper gives a historical rcview of the early research on anelas-ticity during the author,s stay at Chicago (1945-1949).
The rcsearch topicssuggested initially by Professor C. Zener, the founder of the concept of anelas-ticity, include the studies of the mechanical properties of grain boundaries andthe slip bands in metals by anelastic measurements. The torsion pendulum andthe
moving coil twisting arrangement wcrc dcvelopcd for this purpose so that in-ternal friction, dynamics modulus defcct, creep under constant stress and stressrelaxation at a constant strain can be measured with the same specimen.The grain boundary peak(versus temperature)was obscrved for the first time.A "disordered atom groupsn model for high-angle grain boundaries was suggestedmainly in virtue of the succcss in measuring the activation energy associatedwith grain boundary relaxation.Similar internal friction peaks associated with
slip band relaxation wereobserved in partially recrystallized cold-workcd metals. And anomalous internalfriction peaks were discovercd in cold-worked and partially annealed Al-Cu solidsolutions .In conclusion, a short description of the rcscarch performed in China, afterthe Chicago period, on grain boundary relaxation and anomalous internal frictionwas given, including the emergence of non-linear anelasticity.