Mechanical properties of hot pressed CoCrMo alloy compacts for biomedical applications

• CoCrMo hot pressing conditions were evaluated and the influence on mechanical properties were determined.
• At 900 °C compacts showed high porosity, low mechanical strength, low hardness and low Young’s modulus.
• At 1000 °C and 1100 °C compacts showed similar mechanical strength, porosity and Young’s moduli.
• Higher hardness values were registered for 1000 °C compacts when compared to those hot pressed at 1100 °C.
• The 900 °C compacts exhibited brittle behavior while 1000 °C and 1100 °C compacts exhibited ductile behavior.

This study aimed at investigating the influence of the processing conditions on the mechanical properties of hot pressed compacts of a CoCrMo biomedical alloy.Several hot pressed CoCrMo compacts were processed in vacuum (10−2 mbar), at a pressure of 60 MPa with different temperatures (900 °C, 1000 °C and 1100 °C) and different times (10 min, 30 min and 60 min). Compacts were examined by SEM/EDS. The transverse rupture strength, Young’s Moduli and hardness were determined. The fracture surface of compacts were also examined.The compacts hot pressed at 900 °C exhibited lower TRS than those processed at 1000 °C and 1100 °C, which showed similar strength values, regardless the sintering time. The 900 °C compacts showed also lower YM and higher porosity. Lower hardness values were registered for 900 °C compacts while 1000 °C compacts exhibited the highest values. The fracture surface analyses revealed fragile fracture for 900 °C compacts (10 min and 30 min) and 1000 °C (10 min). The remaining compacts exhibited ductile fracture.A full characterization of the mechanical properties of hot pressed CoCrMo compacts has been made and the selection of the processing parameters according to the desired mechanical properties is now possible.

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