Effects of specimen and grain sizes on compression strength of annealed wrought copper alloy at room temperature

• Both grain size effect and feature size effect could be observed in the annealed CuAl7 alloy.
• Compression yield strength of the alloy varied with the t/D ratio in no particular manner.
• If t or D was fixed, the relationship between the t/D ratio and the yield strength was clear.
• The effect of feature size was greater than that of grain size.
• A new model of the relationship between the Rp0.2 and D, t and δ was built.

Variations in compression yield strength of annealed wrought CuAl7 copper alloy with specimen diameter (t) in 1–10 mm range and grain size (D) in 24–172 μm range were investigated. Both grain size effect and feature size effect could be observed. The compression yield strength increased with a reduction in grain size or specimen diameter, and varied with the t/D ratio in no particular manner. However, when t was held constant, the compression yield strength increased as the ratio increased. When D was held constant, the strength decreased as the ratio increased. The Hall–Petch relationship between the compression yield strength and the grain size was found to depend on the specimen diameter. The effect of feature size was greater than that of grain size. A new model of the relationship between the compression yield strength and the grain size, specimen diameter, and size factor has been built. The predicted results of the model agreed well with the experimental results. The fit of the model was better than that of a model based on the relationship between the compression yield strength and the grain size and specimen diameter only.