Would a college dissertation be considered a scholarly article?
A college dissertation would be considered a scholarly work, but a dissertation is different from an article in ways that may be important to you.
A dissertation is usually the length of a book, perhaps 100 pages or more. Scholarly articles are usually much shorter than that.
If it is not already available to you, obtaining a dissertation may be more difficult than obtaining an article. There are far more articles written than dissertations.
Your particular assignment may specifically require scholarly articles rather than Scholarly books or book-length writings, perhaps for the reasons above, perhaps for other reasons.
Check the wording of the assignment. If you still have doubts, check with your instructor.