非平衡Al基合金材料的制备与粉末致密化研究

【作者】 郭晟；

【导师】 黄伯云； 刘咏；

【作者基本信息】 中南大学 ， 材料学， 2005， 硕士

【摘要】 本研究采用快速凝固技术,包括单辊旋淬和紧耦合惰性气体雾化,制备了非平衡Al基合金材料。通过单辊旋淬方法考察Al₈₂Ni₁₀Y₈合金和Al-Ni-Ce-Fe-Cu系合金的非晶形成能力,并分析合金元素对非晶形成能力的影响。从原子拓扑结构角度对Al基合金所特有的极弱非晶形成能力进行了解释,并提出通过小原子的微合金化改善Al基合金的非晶形成能力的思路。利用雾化方法制备了Al₈₂Ni₁₀Y₈,Al₈₆Ni₉Ce₂Fe₁Cu₂,Al₈₇Ni_8.5Ce₃Fe₁Cu_0.5合金粉末,对粉末的显微组织,物相结构和热稳定性以及显微硬度进行了测试,分析了雾化参数对形成非晶粉末的影响。对雾化方法制得Al₈₂Ni₁₀Y₈合金粉末与单辊旋淬方法制得Al₍82_Ni₁₀Y₈合金薄带的冷却速率进行了估算,并在“淬态核”理论基础上估算Al₈₂Ni₁₀Y₈合金形成非晶结构的临界冷却速率约为4.591×10⁵℃/S。系统总结了Al基非晶合金中可能出现的晶化相,并以此分析了Al₈₂Ni₁₀Y₈雾化合金粉末的物相结构。在5个不同温度下对Al₈₂Ni₁₀Y₈雾化合金粉末进行了超高压固结成形,考察块体合金的显微组织演化,以及非晶相和晶体相对致密化的贡献。致密化过程中存在两个相互竞争的过程,即非晶相的粘滞流动和晶化,对这两个过程进行了半定量的分析,认为非晶相的粘滞流动对Al₈₂Ni₁₀Y₈合金粉末的致密化起了更大作用。还研究了热处理对块体Al₈₂Ni₁₀Y₈合金显微组织、物相结构和力学性能的影响。更多还原

【Abstract】 In the investigation, non-equilibrium Al-based materials were prepared using rapid solidification techniques, including melt spinning and close-coupled inert gas atomization. Glass forming ability （GFA） of Al₈2Ni₁0Y₈ and Al-Ni-Ce-Fe-Cu system alloys were analyzed though melt spinning experiments. The effect of alloy elements on GFA was discussed. An assumption of the peculiar marginal GFA of Al-based alloys from the perspective of topological structure of atoms was presented. Based on the assumption, it was suggested that micro-alloying with small-sized atoms into the Al alloys might improve their GFA. Al₈2Ni₁0Y₈, Al₈6Ni₉Ce₂Fe₁Cu₂,Al₈7Ni₈.5Ce₃Fe₁Cu₀.5 powder were prepared by gas atomization and their microstructure, phase assembly, thermal stability and microhardness were tested. The cooling rates of the as-atomized Al₈2Ni₁0Y₈ powder and the melt spun Al₈2Ni₁0Y₈ ribbons were evaluated. The critical cooling rate for Al₈2Ni₁0Y₈ alloys to form amorphous structure was eatimated to be 4.591×10⁵ ℃/s based on the "quenchened-in nuclei" theory. Crystalline phases in Al-based amorphous alloys were systematically summarized and possible phase assembly in Al₈2Ni₁0Y₈ alloy was analyzed. The as-atomized Al₈2Ni₁0Y₈ powder was consolidated at five temperatures under ultra-high pressure. The microstructural evolution of bulk materials was examined and contribution to the densification from amorphous and crystalline phases was analyzed. There existed two competitive processes toward the densification behavior of as-atomized powder, namely viscous flow and crystallization of amorphous phases. Semi-quantitative analysis was made on these two processes and the contribution from the viscous flow to the densification process was more significant. The effect of heat treatment on the microstructure, phase assembly and mechanical of bulk Al₈2Ni₁0Y₈ alloys were also analyzed.更多还原