<p>The study continues a series of articles devoted to development of high-strength aluminum matrix composite reinforced with continuous carbon fibers and to optimization of a new two-stage process for its fabrication. The CF/Al-0.5Bi wire is produced at the first stage by means of rapid melt infiltration accelerated by ultrasonic treatment. Doping with bismuth helps to create weak fiber interfaces and to rise the crack resistance and tensile strength of the wire. At the second stage, bulk composite samples (plates of 50 × 10 × 2 mm) were fabricated from the stack of wire segments by hot pressing at six different temperatures in the range from 640 to 690 °C. This fabrication process has short duration and does not require high pressure in contrast to most liquid-phase pressure infiltration methods. The effect of pressing temperature on the microstructure and mechanical properties of the composite samples were studied in three-point bending tests. The relations between the microstructure, composite strength, interface shear strength, and fracture surface topography of the bulk composite samples and the CF/Al-0.5Bi wire were analyzed to find the optimal temperature yielding the highest strength and other properties. The bulk composite strength and elastic modulus grow with increase in the pressing temperature from 640 to 670 °C. The strength decreases steeply with further temperature increase, the sample fracture surface flattens, and the average fiber pull-out length decreases. The highest average strength is reached for samples pressed at 670 °C and it is equal to 1100 ± 120 MPa. The elastic modulus is 115 ± 10 GPa. The specific strength (strength-to-weight ratio) of the composite is 1.3 times higher than that of any aluminum alloy and 1.5–1.7 times higher than the specific strength of any titanium alloy. The specific stiffness is 2 times higher than specific stiffness of all aluminum or titanium alloys.</p>

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The Impact of Pressing Temperature on the Strength of a Unidirectional CF/AL Composite Produced by a Two-Stage Process

  • S. N. Galyshev,
  • B. I. Atanov,
  • A. V. Khokhlov

摘要

The study continues a series of articles devoted to development of high-strength aluminum matrix composite reinforced with continuous carbon fibers and to optimization of a new two-stage process for its fabrication. The CF/Al-0.5Bi wire is produced at the first stage by means of rapid melt infiltration accelerated by ultrasonic treatment. Doping with bismuth helps to create weak fiber interfaces and to rise the crack resistance and tensile strength of the wire. At the second stage, bulk composite samples (plates of 50 × 10 × 2 mm) were fabricated from the stack of wire segments by hot pressing at six different temperatures in the range from 640 to 690 °C. This fabrication process has short duration and does not require high pressure in contrast to most liquid-phase pressure infiltration methods. The effect of pressing temperature on the microstructure and mechanical properties of the composite samples were studied in three-point bending tests. The relations between the microstructure, composite strength, interface shear strength, and fracture surface topography of the bulk composite samples and the CF/Al-0.5Bi wire were analyzed to find the optimal temperature yielding the highest strength and other properties. The bulk composite strength and elastic modulus grow with increase in the pressing temperature from 640 to 670 °C. The strength decreases steeply with further temperature increase, the sample fracture surface flattens, and the average fiber pull-out length decreases. The highest average strength is reached for samples pressed at 670 °C and it is equal to 1100 ± 120 MPa. The elastic modulus is 115 ± 10 GPa. The specific strength (strength-to-weight ratio) of the composite is 1.3 times higher than that of any aluminum alloy and 1.5–1.7 times higher than the specific strength of any titanium alloy. The specific stiffness is 2 times higher than specific stiffness of all aluminum or titanium alloys.