350 Prakt. Met. Sonderband 52 (2018) 
nanoliters) and its surface area to be 545,000 um? (0.545 mm?). Higher 3D image resolution oo 
can be obtained if 2D images are recorded more frequently after fewer milling steps, e.g., if a 
after every 2 milling steps an image is recorded, then only 20 um of alloy (2 steps of 10 um) Ce 
would be removed. A 
0050 
ne 3D 
Refer 
Figure 3: 3D image of the Al alloy macroscale defect generated using the LAS X 3D os 
Visualization software from Leica Microsystems: A) 3D image reconstructed from the 2D LR 
image stack (total 40 images); B) Image of alloy sample cross section showing the defect’s 
measured volume (0.429 x 10 mm?) and surface area (0.545 mm?2); and C) Zoom-in onto { 
the defect seen in image B- 
11. 
4. Summary and Conclusions 
This report described a method to image macroscale defects in non-transparent aluminum 
(Al) alloys in 3-dimensions (3D) with milling and optical microscopy. 
Because Al alloys are important for the manufacture of aircraft and vehicles, as well as other 
products, thorough alloy characterization can help to minimize or eliminate defects which 
can affect quality and performance. 
3D-images of a defect in an opaque Al alloy were produced using the following approach: 
* An Al alloy sample with a macroscopic defect was milled in small steps (10 pm thickness); 
+ 2D optical microscopy images of the milled alloy surface were recorded after each time a 
thickness of 50 um was removed; 
» Atotal of 2 mm of alloy was milled away, yielding a total of 40 images in 2D; and 
» A 3D image of the alloy and defect was reconstructed from the stack of 2D images.