Sliding member

A sliding member comprising:

• a back-metal layer having a back surface and a bonding surface;
• and
• a sliding layer on the bonding surface of the back-metal layer, the sliding layer having a sliding surface,
• wherein the back-metal layer comprises an Fe alloy,
• wherein the sliding layer comprises a copper alloy comprising 0.5 to 12 mass % of Sn and the balance of Cu and inevitable impurities,
• wherein the sliding member has a cross-sectional structure perpendicular to the sliding surface, the cross-sectional structure comprising first copper alloy grains that are in contact with the bonding surface and second copper alloy grains that are not in contact with the bonding surface,
• wherein the first copper alloy grains have an average grain size D1 and the second copper alloy grains have an average grain size D2, and D1 and D2 satisfy the following relations:
• D1 is 30 to 80 μm;
• and
• D1/D2 =0.1 to 0.3,
• wherein, in the cross-sectional structure, the second copper alloy grains comprise third grains, each of which includes internal grains and another grain portion therein, and the internal grains are not in contact with grain boundaries of the each of the third grains, and
• wherein a total area S0 of the third grains and a total area S2 of the second copper alloy grains satisfy the following relation:
• S0/S2=0.25 to 0.80.