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<p>Hypereutectic Al-Si alloys are widely applied in automotive and aerospace industries due to their high formability, high strength, and high wear resistance attributed to the high content of hard Si phases. However, their performances are frequently limited by the presence of coarse primary Si particles and weak matrix–particle interfaces. The effects of TiB<sub>2</sub> addition on the microstructure, mechanical properties, and wear behavior of the AlSi15Mg alloy were systematically investigated. The results indicated that TiB<sub>2</sub> effectively refined the Si phase morphology, with the optimal refinement achieved at 0.8&#xa0;wt% TiB<sub>2</sub>. At this content, the Si phase transforms from elongated flakes, short rods, and fibrous structures with 7.96 ± 3.19&#xa0;μm into uniformly refined short rods with 4.38 ± 1.91&#xa0;μm. Owing to grain refinement and Orowan strengthening induced by the well-dispersed TiB<sub>2</sub> particles, the ultimate tensile strength increased from 150.62&#xa0;MPa to 211.00&#xa0;MPa and the hardness increased from 92.76 HV to 108.46 HV. The wear resistance of the alloy reached its optimum at 0.8 wt% TiB<sub>2</sub>, with the coefficient of friction decreasing from 0.79317 to 0.68528 and the wear rate decreasing from 4.18 × 10<sup>–5</sup>&#xa0;(mm<sup>3</sup>/(N∙m)) to 2.13 × 10<sup>–5</sup>&#xa0;(mm<sup>3</sup>/(N∙m)). The addition of TiB<sub>2</sub> reduced stress concentration at Si particles, suppressed their brittle fracture and delamination during sliding, and enhanced load-bearing capacity due to the high intrinsic hardness of TiB<sub>2</sub>. However, excessive TiB<sub>2</sub> addition (1.0&#xa0;wt%) led to particle agglomeration and ultimately deteriorated the mechanical and tribological performance.</p>

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Effect of TiB2 on the microstructure, mechanical properties, and wear properties of AlSi15Mg alloy

  • 期刊论文

  • 发表日期：

    2026年4月6日

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  • Yecheng Yan,
  • Siqi Yin,
  • Xiulan Ai,
  • Guangzong Zhang,
  • Shuo Zhang,
  • Guodong Shi,
  • Renguo Guan

摘要

Hypereutectic Al-Si alloys are widely applied in automotive and aerospace industries due to their high formability, high strength, and high wear resistance attributed to the high content of hard Si phases. However, their performances are frequently limited by the presence of coarse primary Si particles and weak matrix–particle interfaces. The effects of TiB2 addition on the microstructure, mechanical properties, and wear behavior of the AlSi15Mg alloy were systematically investigated. The results indicated that TiB2 effectively refined the Si phase morphology, with the optimal refinement achieved at 0.8 wt% TiB2. At this content, the Si phase transforms from elongated flakes, short rods, and fibrous structures with 7.96 ± 3.19 μm into uniformly refined short rods with 4.38 ± 1.91 μm. Owing to grain refinement and Orowan strengthening induced by the well-dispersed TiB2 particles, the ultimate tensile strength increased from 150.62 MPa to 211.00 MPa and the hardness increased from 92.76 HV to 108.46 HV. The wear resistance of the alloy reached its optimum at 0.8 wt% TiB2, with the coefficient of friction decreasing from 0.79317 to 0.68528 and the wear rate decreasing from 4.18 × 10–5 (mm3/(N∙m)) to 2.13 × 10–5 (mm3/(N∙m)). The addition of TiB2 reduced stress concentration at Si particles, suppressed their brittle fracture and delamination during sliding, and enhanced load-bearing capacity due to the high intrinsic hardness of TiB2. However, excessive TiB2 addition (1.0 wt%) led to particle agglomeration and ultimately deteriorated the mechanical and tribological performance.