Exhibit 5.1

September 1, 2026

Ladies and Gentlemen:

I am Senior Vice President, General Counsel – North America Operations, and Secretary of Alcoa Corporation, a Delaware corporation (“Alcoa”), and am rendering this opinion in connection with the registration statement on Form S-4 (the “Registration Statement”) to be filed with the Securities and Exchange Commission (the “SEC”) on the date hereof under the Securities Act of 1933, as amended (the “Act”), and the registration by Alcoa of shares of common stock, par value $0.01 per share, of Alcoa (“common stock”) in connection with Alcoa’s proposed acquisition of the equity interests of South32 Limited (“South32”) in bauxite mine, alumina refinery and certain aluminum smelter operations (the “Transaction”) pursuant to the Umbrella Implementation Deed, dated as of June 30, 2026 (the “Transaction Agreement”), by and among Alcoa, the buying entities party thereto, South32 and the selling entities party thereto.

I, or members of my staff, have reviewed such corporate records, certificates, and other documents, and such questions of law, as we have considered necessary or appropriate for the purposes of this opinion.

In my examination, I have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to me as originals, the conformity to original documents of all documents submitted to me as copies and the authenticity of the originals of such documents. In making my examination of executed documents, I have assumed that the parties thereto, other than Alcoa, its subsidiaries, its directors and officers, had the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and execution and delivery by such parties of such documents and the validity and binding effect thereof on such parties. As to any facts material to the opinion expressed herein which I have not independently established or verified, I have relied upon oral or written statements and representations of officers and other representatives of Alcoa and others.

For purposes of this opinion, I have further assumed that prior to the issuance of any shares of common stock in connection with the Transaction: (i) the Registration Statement, as finally amended, will have become effective under the Act and such effectiveness will not have been terminated or rescinded or be subject to any stop order; and (ii) the Transaction contemplated by the Transaction Agreement will have been consummated in accordance with the terms and conditions of the Transaction Agreement.

Based upon and subject to the foregoing, I am of the opinion that the shares of common stock, when issued and delivered in accordance with the terms and conditions of the Transaction Agreement, will be validly issued, fully paid, and non-assessable.

This opinion is limited to Delaware General Corporation Law, and I express no opinion with respect to any other laws. This opinion is delivered as of the date hereof, and I undertake no obligation to advise you of any changes in applicable law or any other matters that may come to my attention after the date hereof.

I hereby consent to the filing of this opinion with the SEC as an exhibit to the Registration Statement. I also consent to the inclusion of my name under the caption “Validity of Common Shares” in the Registration Statement. In giving this consent, I do not thereby admit that I am included in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the SEC.