共查询到20条相似文献,搜索用时 9 毫秒
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Yuliang Zhao Weiwen Zhang Dongfu Song Bo Lin Fanghua Shen Donghai Zheng ChunXiao Xie Zhenzhong Sun Yanan Fu Runxia Li 《材料科学技术学报》2021,80(21):84-99
Plate-like Fe-rich intermetallic phases directly influence the mechanical properties of recycled Al alloys;thus,many attempts have been made to modify the morphology of these phases.Through synchrotron X-ray imaging and electron microscopy,the underlying nucleation and growth mechanisms of Fe-rich phases during the solidification of Al-5Ti-1B-modified Al-2Fe alloys were revealed in this study.The results showed that the Al-5Ti-1 B grain refiner as well as the applied pressure both resulted in reduction of the size and number of primary Al3Fe phases and promoted the formation of eutectic Al6Fe phases.The tomography results demonstrated that Al-5Ti-1B changed the three-dimensional (3D) morphology of primary Fe-rich phases from rod-like to branched plate-like,while a reduction in their thickness and size was also observed.This was attributed to the fact that Ti-containing solutes in the melts inhibit the diffusion of Fe atoms and the Al3Fe twins produce re-entrant corner on the twin boundaries along the growth direction.Moreover,the TiB2 provides possible nucleation sites for Al6Fe phases.The nucleation mechanism of Fe-rich phases is discussed in terms of experimental observations and crystallography calculations.The decrease in the lattice mismatch between TiB2 and Al6Fe phases was suggested,which promoted the transformation of Al3Fe to Al6Fe phases. 相似文献
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铁基合金中以氏体均匀形核热力学探讨 总被引:1,自引:0,他引:1
根据马氏体相变的经典形核理论,重新对铁基合金是马氏体相变的形核过程进行了热力学估算,结果表明,均匀形核的临界形核功比热能低一个数量级。这意味着铁基合金中的马氏体相变形核可由热起伏来促发。对早期的小颗粒实验以及铁基体材料中马氏体相变的相关实验结果进行了分析讨论,表明均匀形核机制和这些实验结果相一致。 相似文献
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铁基合金中马氏体形核动力学探讨 总被引:2,自引:0,他引:2
根据马氏体相变的经典形核理论,重新估算了铁基合工中马氏体均匀形核激活能,研究了激活能与界面能和相变驱动力的关系。结果表明,热激活形核具有很低的形核激活能,热激活能形核动力学与马氏体形核动力学实验研究结果一致,在动力学研究的基础上,提出了马氏体相变的形核机制,在形核机制中,除了热激活菜核,还考虑了应力对马氏体形核的作用,特别是在低温时由于急应内应力对形核的贡献。 相似文献
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镍衬底上定向金刚石膜的成核与生长 总被引:2,自引:0,他引:2
提出了一种包括晶粒接种、高温退火、成核、生长四过程的薄膜沉积新方法 ,用射频等离子体增强热丝化学气相沉积系统 ,在Ni衬底上制备了定向金刚石膜。通过对成核和生长两过程工艺条件的研究 ,掌握了提高成核密度和金刚石定向生长规律。实验还表明 ,膜与Ni衬底之间未见Ni C H界面层的形成 相似文献
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本文对泡沫塑料的成型机理进行了全面综合的分析,指出发泡成型各个阶段的机理及影响泡体性能和质量的因素,还把现有的各种发泡成型方法的成核过程归纳为三大类,指出每一类的成核机理,使用范围及主要影响参数,为进一步的深入研究提供参考。 相似文献
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The heterogeneous nucleation behaviors of NH4Cl crystal on rough aluminum substrate surface immerged in NH4Cl-H2O solution were experimentally analyzed, and the influence mechanism of the micro/nano-scale surface structures on heterogeneous nucleation was investigated. It has been shown that wettability and nucleation are affected by substrate surface condition. The intrinsic wetting properties between nucleus and substrate surface, and the surface structure of certain geometrical scales, both impose effects on the heterogeneous nucleation properties. For a nucleus-wetting substrate surface, heterogeneous nucleation is promoted by a higher complexity of the surface morphology; but for a nucleus-nonwetting substrate surface, heterogeneous nucleation is inhibited by a higher complexity of the surface morphology. 相似文献
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钪在铝及铝合金中的作用 总被引:19,自引:3,他引:16
总结了Sc在铝及铝合金中对合金组织、力学性能、热稳定性、焊接性能和抗腐蚀,性能的影响。Sc在铝合金中是有效的晶粒细化剂、再结晶抑制剂和改善焊接性能的添加剂;Sc可以细化铝合盒晶粒,提高合盒的力学性能和再结晶温度,增强铝合金的热稳定性,改善铝合盒的焊接性能和抗腐蚀性能;分析了Sc在铝合盒中的作用机理。 相似文献
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(NaPO3)n对过共晶Al-Si合金初晶硅细化的研究 总被引:1,自引:1,他引:0
研究了 (Na PO3) n 对 Al- 2 2 % Si过共晶合金初晶硅的晶粒细化作用。结果表明 ,(Na PO3) n对初晶硅的细化效果优于 Cu P,同时 (Na PO3) n 具有共晶硅变质的作用。采用 (Na PO3) n 处理的 Al- 2 2 % Si- 1.0 % Cu- 0 .5 % Mg- 0 .5 % Mn合金的平均抗拉强度可达 2 73MPa。以扫描电镜、电子探针为检测手段研究了 P元素对过共晶 Al- Si合金的 Si晶体的影响。结果表明 ,一方面 Al P作为异质核心细化初晶硅 ,另一方面 ,有 Na同时存在时 ,P的扩散受阻 ,P元素在 Si相生长表面富集 ,阻碍了 Si相生长 ,细化了初晶硅。 相似文献
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铝基非晶合金因其独特的物理和化学性能在诸多领域具有广泛的应用前景,综述了铝基非晶合金的成分体系、制备方法、性能特点及应用研究进展。首先,介绍了铝基非晶合金的发展历史和成分体系,目前铝基非晶主要分为3大体系:二元、三元和多元体系,以及综合性能和形成能力2大方面,多元体系表现更佳,并逐渐向更多元化发展;其次,系统介绍了铝基非晶合金的制备方法,包括粉末状、薄带状、块体样品的制备,相较于非晶薄带的制备,块体和粉状的制备方法较为丰富,而粉状非晶通常作为铝基非晶涂层的预制材料;随后,详细介绍了铝基非晶合金的性能特点、应用现状及发展趋势,从性能上来看,铝基非晶在强度和硬度以及耐腐蚀性能上表现良好,目前主要以涂层的形式参与应用,除此之外,研究者们也开始对磁性和热塑性展开研究,由于玻璃形成能力的限制,作为结构材料的应用较少;最后,对其未来应用前景进行了展望,认为涂层是目前铝基非晶合金最具应用前景的工程化方式。 相似文献
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利用热丝化学气相沉积法 (HF CVD)进行了金刚石薄膜制备和碳纳米管形核作用的研究。获得了制备金刚石薄膜的优化工艺参数。利用碳纳米管作为形核前驱获得了高质量的金刚石薄膜 ,其沉积速率可达 2 5 μm/h ,晶粒生长完美 ,而且没有出现聚晶现象。研究了碳纳米管涂料质量对薄膜沉积特性的影响 ,并对其机理进行了初步探讨 相似文献
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Zhongwei CHEN Zhi HE Wanqi JIE 《材料科学技术学报》2007,23(5):619-622
Based on the assumption that the nucleation substrates are activated by constitutional undercooling generated by an adjacent grain growth and solute distribution during the initial solidification, a model for calculation of the grain size of aluminum alloys with the grain refinement is developed, where the nucleation is dominated by two parameters, i.e. growth restriction factor Q and the undercooling parameter P. The growth restriction factor Q is proportional to the initial rate of constitutional undercooling development and can be used directly as a criterion of the grain refinement in the alloys with strong potential nucleation particles. The undercooling parameter P can be regarded as the maximum of constitutional undercooling △Tc. For weak potential nucleation particles, the use of RGS would be more accurate. The experimental data of the grain refinement of pure aluminum and AlSi7 alloys are coincident predicted results with the model. 相似文献