热轧高含量B_(4)C颗粒增强Al基复合材料的成形性能

Formability of high content B_(4)C particle reinforced Al matrix composites by hot rolling

高含量B_(4)C(B_(4)C≥30wt%)颗粒增强Al基(B_(4)C_(P)/Al)复合材料具有优异的结构和功能特性,尤其是具有优异的中子吸收性能,在核防护领域被用做屏蔽材料使用。但由于高含量B_(4)C颗粒的加入,使B_(4)C_(P)/Al复合材料变形困难。采用ABAQUS数值模拟方法对不同变形量下B_(4)C_(P)/Al复合材料的热轧过程进行数值模拟分析,在480℃温度下对热压烧结的B_(4)C_(P)/Al复合材料坯料进行轧制,并对其微观组织和力学性能进行分析。数值模拟结果表明,热轧变形量达到60%以上时,B_(4)C_(P)/Al复合材料板材表面中间区域应力较小,侧面应力较大,在板材边缘容易产生残余应力。研究结果表明,随轧制下压量的增加,B_(4)C_(P)/Al复合材料中B_(4)C颗粒分布明显均匀,位错密度增加。当轧制变形量达到70%时,B_(4)C_(P)/Al复合材料的屈服强度提高至249.46 MPa,极限抗拉强度提高至299.56 MPa。在拉伸过程中,B_(4)C颗粒优先断裂,但并未与基体界面脱黏,B_(4)C颗粒承受了主要载荷,Al基体发生塑性流动,从而提高了B_(4)C_(P)/Al复合材料的强度。

The high content B_(4)C(B_(4)C≥30wt%)particle reinforced Al matrix(B_(4)C_(P)/Al)composites have excellent structural and functional properties,especially excellent neutron absorption performance,and are used as shielding materials in the field of nuclear protection.However,due to the addition of the high content B_(4)C particles,the deformation of the B_(4)C_(P)/Al composites is difficult.ABAQUS numerical simulation method was used to simulate the hot rolling process of B_(4)C_(P)/Al composites under different deformations.The B_(4)C_(P)/Al composites fabricated by hot pressing sintering were rolled at 480℃and its microstructure and mechanical properties were analyzed.The numerical simulation results show that when the hot rolling deformation reaches more than 60%,the stress in the middle area of the B_(4)C_(P)/Al composite plate surface is small,while the stress in the side is large,and the residual stress is easily generated at the edge of the plate.The results show that B_(4)C particles in B_(4)C_(P)/Al composites distribute uniformly and the dislocation density increases with the increase of rolling deformation.When the rolling deformation reaches 70%,the yield strength of the B_(4)C_(P)/Al composite increases to 249.46 MPa and the ultimate tensile strength increases to 299.56 MPa.In the tensile process,the B_(4)C particles have the priority to fracture without the desorbed interface with the matrix.The B_(4)C particles bear the main stress,and the Al matrix has plastic flow,thus improving the strength of the B_(4)C_(P)/Al composites.