Ceramic-aluminum conjugate, power module substrate, and power module

A ceramic-aluminum bonded body comprising:

• a ceramic member made of AlN;
• and an aluminum member, the ceramic member and the aluminum member being bonded together, wherein
• Mg-containing oxides having a spinel crystal structure are dispersed in the aluminum member within a range of 2 μm in a thickness direction from a bonded interface with the ceramic member,
• a segregated portion in which Mg, Si, and O are segregated is formed in the aluminum member in the vicinity of the bonded interface with the ceramic member,
• ratios of an amount of Mg [Mg]S, an amount of Si [Si]S, and an amount of O [O]S in the segregated portion to an amount of Mg [Mg]I, an amount of Si [Si]I, and an amount of O [O]I, respectively, at a position spaced by 10 μm from the bonded interface toward an aluminum member side are within ranges of
• 1<[Mg]S/[Mg]I≤15,
• 1<[Si]S/[Si]I≤25, and
• 1<[O]S/[O]I≤25, and
• the amount of Mg [Mg]I at the position spaced by 10 μm from the bonded interface toward the aluminum member side is 0.8 mass % or less.