Sometimes you may stumble upon a curved feature that appears to be made of multiple flat surfaces.
If you notice this with imported files:
Check the export settings of whichever program you used to originally create the file.
Some programs create coarse faceting depending on their export values for different filetypes. This usually helps to reduce file size, but can have undesired results in the final geometry. This generally can not be corrected in Alibre Design as the problem does not originate there.
If you notice this with a native Alibre Design part:
You may notice when designing a part that your curves appear a little coarsely defined, as in the below picture. This is, in fact, usually the case. Curvature is controlled by a file property called the Facet Resolution. Lower facet resolutions result in increasingly coarse curve geometry.
Click the Alibre Gem to bring up the File Properties dialog, and go to Display. Your facet resolution settings might be set to Coarse.
To correct the problem, adjust your facet resolution up to Fine. Click Apply then close the dialog. Regenerate the part, and you'll see the curves smooth out, as in the below picture.