采用三维高效混料机混料、多级真空热压和热挤压制备了增强体含量为6 vol%的纳米B4CP(n-B4CP,50 nm)/2009Al复合材料,研究复合材料中n-B4CP分布、形成机制以及对n-B4CP/2009Al复合材料力学性能的影响.结果表明:当混料球料比为5∶1时,复合粉末经过30 h混料后,纳米B4CP基本均匀分布于Al合金颗粒表面;热压态复合材料中n-B4CP偏聚在基体晶界处,经过热挤压后,复合材料中的n-B4CP呈弥散均匀分布.热挤压过程中,基体合金的塑性流动对分布于晶界处的纳米B4CP形成剪切作用力,断裂的纳米B4CP团聚体沿着剪切应力方向发生重新分布是实现n-B4CP均匀分布的主要机制.经过495℃保温1 h后水淬,175℃人工时效16 h后,增强体含量为6 vol% n-B4CP/2009Al复合材料硬度比基体合金提高了36.4%,抗拉强度和屈服强度分别提高10.9%和26.2%.n-B4CP/2009Al复合材料的拉伸断口表现出韧性断裂和脆性断裂混合特征.
To provide basic comprehension into formation mechanism and spatial distribution of the nano-B4CP(n-B4CP,50nm), as well as the influence of nano-particle distribution on mechanical properties of 6 vol% n-B4CP/2009Al composite.6 vol% B4C nanoparticles reinforced 2009Al matrix(6 vol% n-B4CP/2009Al) composite was fabricated by efficient 3D mixermulti-stage vacuum hot pressing and hot extrusion method.The results show that, when the ball charge mass ratio is 5∶1, B4C nanoparticles can be distributed uniformly on the surface of Al alloy powders after 30 h milling.The B4C nanoparticles of 6 vol% n-B4CP/2009Al composite in hot pressing state segregate at the matrix boundary, which are uniformly distributed after hot extrusion.During hot extrusion process, the chief mechanism of homogenizing B4C nanoparticles is that the plastic flow of alloy matrix impose a shear pressure upon B4C nanoparticles at the matrix boundary and then the cracked B4C nanoparticles aggregates redistributed along the direction of the shear force.After a solution treatment at 495℃ for 1 h,followed by water quenching and artificial aging at 175℃ for 16 h, the hardness of 6 vol% n-B4CP/2009Al composite is 36.4% higher than that of pure 2009Al alloy, and tensile strength and yield strength increase 10.9% and 26.2% respectively.The tensile fracture surface of 6 vol% n-B4CP/2009Al composite reveals a mixing characteristic of ductile and brittle fractures.
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