Answer
Every alloy of copper ( Cu +other metal(s)) is necessarily harder (higher strength) than pure copper by itself, with some elements having much higher strengthening effects than others due to the metallic compounds that may be formed during solidification or heat treating.
Work Step by Step
Tin atoms area different size than copper and when dissolved in molten copper and subsequently frozen, the resulting crystal structure is significantly different producing a microstructure that is more resistant to deformation .
