Electromigration is inevitable in electronic products and detrimental to the reliability. However, we present in this study an innovative material treatment using cyclic direct current stressing for the manipulation of the microstructure and material properties of metals by introducing the basic electromigration theory. The experiment using a pure Al metal was designed to prevent possible interference from complex precipitation occurrence upon the treatment. The present work evidenced the electro-hardening of metals accompanying electrical resistance enhancement upon the cyclic direct current stressing treatment. The cyclic treatment with repeated direct current stressing and liquid nitrogen quench is capable of controlling the grain size and thus the material properties through the competition between the recrystallization (athermal effect dominated) and grain growth (thermal effect dominated) mechanisms. A combined tD (duration time) over n (cycle) parameter describing the energy input per unit cycle is proposed as an efficient index for the optimal properties achievement. In comparison with the conventional electropulsing treatment, the novel treatment as proposed can be applied for testing subjects without the need for a macroscopic deformation pre-treatment.
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