Size effects on tensile strength of aluminum–bronze alloy at room temperature

• Effects of both grain and feature size could be observed on tensile yield strength of the alloy.
• The grain size effect was greater than the feature size effect in terms of statistics theory.
• Size effect intensity on compression strength was larger than that on tensile strength.
• Thickness value of 0.50 mm represents a dividing point with respect to the feature size effect.

Variations in tensile yield strength of annealed CuAl7 copper alloy were investigated. Both grain and feature size effects could be observed. Statistical analysis revealed that the grain size effect was greater than the feature size effect. The grain size effect on the tensile yield strength of the alloy was very significant. The feature size effect was very significant or significant when the specimen thickness was no more than 0.50 mm, while the effect was insignificant or completely absent when the specimen thickness was greater than 0.50 mm. In addition to grain size d and specimen thickness t, the t/d ratio of the specimen can also affect the tensile yield strength. The tensile yield strength of the alloy was almost a constant when the t/d ratio was greater than a critical value (approximately 21). Otherwise, the strength tended to increase with an increasing value of t/d, except for the specimen with a thickness of 0.25 mm. The size effects on the tensile strength of the CuAl7 copper alloy were compared with the effects on the compression strength. It was found that the size effect intensity on the compression yield strength was greater than that on the tensile yield strength.

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