Yttrium-excess Y x Ba2Cu3O y (1.00≤x≤1.25) superconductors have been fabricated by a combination process of ordinary solid-state reaction and partial melting. Sintering the yttrium-excess Y x Ba2Cu3O y results in extremely small grains, which in turn produce uniformly distributed fine Y2BaCuO5 during partial melting. Y2BaCuO5 acts as the nucleation site for peritectic reaction. The unreacted Y2BaCuO5 seems to act as a flux pinning center. Due to this flux pinning force, the yttrium-excess Y x Ba2Cu3O y superconductors have very high critical current densities of about 22,000 A/cm2 (at 77 K, 1 T).