Advanced Micro Devices Inc. struck another blow at Intel Corp., its bigger rival in the market for personal-computer microprocessors, as it disclosed plans Monday to buy one of the dominant makers of graphics chips in a $5.4 billion deal that analysts said could fundamentally alter competition in the semiconductor industry.

The acquisition of ATI Technologies Inc. will allow AMD to shed its role as a boutique player that sells only microprocessors, which act as the core calculating engines in PCs. Almost immediately, AMD will become a seller of chips in four new categories, eroding a key advantage of Intel, which has long benefited from its broader product portfolio.