3.2. HardnessTable 2 shows the thickness of the samples, the a-Al grain sizeand the Vickers hardness. In order to appreciate the slight differentof the microstructure obtained on both ribbon's side, the a-Al grainsize and the hardness of the melt-spun samples were measured onboth the WS and GS. On the GS, the a-Al grain size is slightly largerand the hardness is lower, with a larger variation of ~10 HV0.3.It is observed that as the thickness of the samples decreases thea-Al grain size decreases and the hardness increases. However, theSR7 samples show lower hardness than the SR1.5 samples.