Structure and property relationships for bulk electrodeposits

Abstract

The properties of bulk electrodeposits depend on structure. Fine-grained deposits exhibit greater strength than coarse, columnar structures. For example, the tensile strengths of fine-grained copper and nickel reach values as high as 90 000 and 150 000 psi, respectively, in comparison with only 25 000 and 50 000 psi for the coarser-grained deposits. Analogously, the tensile strengths of fine-grained cobalt, gold, iron, and silver can be two to five times the strength of the coarse-grained counterpart. Nickel containing 0.02% sulfur (as nickel sulfide) exhibits a tensile strength as high as 235 000 psi. Some metals deposited at a high rate (> 0.001 in./min) are finer grained and stronger than their counterparts deposited conventionally at a rate < 0.00005 in./min. The physical properties of the fine-grained structures are dependent on the conditions adopted for refining grain size. High density, low electrical resistivity, and good thermal stability can be obtained with conditions that avoid undesirable inclusions.