Brainship #1: The Ship Who Sang by Anne McCaffrey

Helva had been born human, but only her brain had been saved—saved to be schooled, programmed, and implanted into the sleek titanium body of an intergalactic scout ship. But first she had to choose a human partner—male or female—to share her exhilarating escapades in space!
Her life was to be rich and rewarding . . . resplendent with daring adventures and endless excitement, beyond the wildest dreams of mere mortals.

Gifted with the voice of an angel and being virtually indestructible, Helva XH-834 anticipated a sublime immortality.

Then one day she fell in love!