Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化...Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。展开更多
This study investigates the combustion characteristics of reactive aluminium alloys in combination with fluoropolymer oxidizers. Aluminium-magnesium(Al-Mg) and aluminium-titanium(Al-Ti) alloys were selected as metalli...This study investigates the combustion characteristics of reactive aluminium alloys in combination with fluoropolymer oxidizers. Aluminium-magnesium(Al-Mg) and aluminium-titanium(Al-Ti) alloys were selected as metallic fuels, while polyvinylidene fluoride(PVDF) was employed as the oxidizer. Composite samples were prepared using two methods: electrostatic spraying(ES) and physical mixing(PM). The ES method yielded samples with a PVDF-coated structure, whereas the PM method produced simple mixtures. The samples and their combustion products were characterized using scanning electron microscopy(SEM), X-ray diffraction(XRD), combustion experiments, and thermal analysis. The results indicate that compared to the PM samples, the ES-coated samples exhibited more effective dispersion of metallic particles, reduced particle agglomeration, increased combustion heat release temperature, decreased maximum flame area and height, and mitigated or eliminated explosive or micro-explosive phenomena during combustion, thereby achieving stable combustion. Additionally, the ES samples demonstrated a significant reduction in the particle size of condensed-phase products after combustion, alleviated sintering and agglomeration, decreased the formation of metal oxides, and minimized residual metallic fuel, allowing for the full release of combustion heat. Thermal analysis revealed that the coating structure of the ES samples lowered the activation energy for the reaction between the metallic fuel and PVDF, thereby enhancing the chemical reactivity.展开更多
文摘Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。
基金National Natural Science Foundation of China (NSFC,Grant Nos.52176114 and 52306145)Natural Science Foundation of Jiangsu Province (Grant No.BK20230929)+2 种基金China Postdoctoral Science Foundation (Grant No.2024M764222)Fundamental Research Funds for the Central Universities (Grant No.30924010505)Jiangsu Funding Program for Excellent Postdoctoral Talent。
文摘This study investigates the combustion characteristics of reactive aluminium alloys in combination with fluoropolymer oxidizers. Aluminium-magnesium(Al-Mg) and aluminium-titanium(Al-Ti) alloys were selected as metallic fuels, while polyvinylidene fluoride(PVDF) was employed as the oxidizer. Composite samples were prepared using two methods: electrostatic spraying(ES) and physical mixing(PM). The ES method yielded samples with a PVDF-coated structure, whereas the PM method produced simple mixtures. The samples and their combustion products were characterized using scanning electron microscopy(SEM), X-ray diffraction(XRD), combustion experiments, and thermal analysis. The results indicate that compared to the PM samples, the ES-coated samples exhibited more effective dispersion of metallic particles, reduced particle agglomeration, increased combustion heat release temperature, decreased maximum flame area and height, and mitigated or eliminated explosive or micro-explosive phenomena during combustion, thereby achieving stable combustion. Additionally, the ES samples demonstrated a significant reduction in the particle size of condensed-phase products after combustion, alleviated sintering and agglomeration, decreased the formation of metal oxides, and minimized residual metallic fuel, allowing for the full release of combustion heat. Thermal analysis revealed that the coating structure of the ES samples lowered the activation energy for the reaction between the metallic fuel and PVDF, thereby enhancing the chemical reactivity.
