【作者】 胡勇；

【导师】 陈学定；

【作者基本信息】 兰州理工大学 ， 材料加工， 2004， 硕士

【摘要】 本文以Al—Ni—Zr系列非晶合金为研究基础，通过添加稀土元素Y和过渡族元素Cu分别在大气和真空环境条件下采用旋铸急冷工艺制各出四元Al—Ni—Zr—Y，五元Al—Ni—Zr—Cu—Y合金条带，利用X射线衍射、SEM和示差扫描量热仪（DSC）等测试仪器对合金条带淬火态和退火态的组织、显微结构及非晶形成能力和热稳定性等进行了研究。研究结果表明：设计的Al₈₅Ni₈Zr₃Cu₂Y₂合金与Al₈₅Ni₁₀Zr₅合金相比较其非晶形成能力和热稳定性都有所提高。与此同时，快凝Al₈₅Ni₁₀Zr₅合金和Al₈₅Ni₈Zr₃Cu₂Y₂合金在真空和大气条件下都形成了展宽的非晶漫散射峰和以非晶漫散射峰为主，衍射峰上重叠部分晶体相的曲线，且两种条件下，Al₈₅Ni₁₀Zr₃合金在漫散射峰上有a-Al的晶体衍射峰呈现，而Al₈₅Ni₈Zr₃Cu₂Y₂合金呈现展宽的非晶漫散射峰，说明快凝环境对Al—Ni—Zr、Al—Ni—Zr—Cu—Y合金系的非晶形成影响不大。 进一步的研究发现，快凝Al—Ni—Zr合金中，稀土元素Y的添加，促进了a-Al相和化合物相的析出，降低了合金系的非晶形成能力。同时，合金的初始晶化温度有所提高，说明添加稀土元素Y后Al—Ni—Zr合金的热稳定性增加了。而在快凝Al—Ni—Zr—Y合金的基础上，添加适量的过渡族元素Cu有效降低了a-Al相和化合物相的析出，提高了合金系的非晶形成能力。然而在zr、过渡族元素Ni和稀土元素Y含量一定的情况下，随着过渡族Cu元素含量的提高，合金系的非晶形成能力和热稳定性都降低了。研究中还发现，Al—Ni—Z—Cu—Y系合金的DSC曲线中并没有明显的玻璃转变温度T_g所对应的核化吸热峰存在，因而导致过冷液相区的消失，这主要是由于淬火核的存在导致核化阶段所对应的吸热过程消失所造成的。从Al₈₅Ni₈Zr₃Cu₂Y₂完全非晶合金在初始晶化温度处保温30min的退火态SEM图和Al₈₅Ni₁₀Zr₅合金淬火态的SEM图可以看出，控制合金熔体的冷却速率和选择非晶合金合适的退火工艺都可以获得纳米级a-Al相均匀分散在非晶基体上的复合结构。更多还原

【Abstract】 This paper reports the results of investigation into the formation and thermal stability of the amorphous Al-Ni-Zi-Y and Al-Ni-Zi-Cu-Y alloy ribbons Prepared by melt spinning method under vacuum and atmosphere conditions. As-melt-spun amorphous alloy ribbons and quench amorphous alloy ribbons’ tissue and microstructures and GFA were investigated by x-ray diffraction and scanning electron microscopy and differential scanning calorimetry (DSC). It is found that addition of Yttrium and Copper element into Al85Ni8Zr3Cu2Y2 amorphous alloy increases the GFA and thermal stability of Al85Ni10Zr5 alloy apparently. At the same time It could find no matter in vacuum or atmosphere conditions similar X-ray diffraction patterns were obtained from both alloy ribbons. All traces show the broad amorphous peak, indicating the existence of a single amorphous phase or primary amorphous phase structure. The different is that there are sharp peaks superimposed the broad amorphous peak and the peak of crystalline phase is demarcated as the face-centered-cubic Al (a-Al)). Compare with the processing conditions, composition and cooling rate play an important role in formation of Al-Ni-Zi-Cu-Y amorphous alloys.It also can find that the addition of Y promote the formation of a-Al and compound phase, which reduce the GFA of Al-Ni-Zr alloy. On the contrary increase the crystal temperature of Al-Ni-Zr alloy, on the basic of Al-Ni-Zi-Y alloy, the addition of suitable Cu element can reduce the formation of a-Al and compound phase effectively. At the same time Increase the formation ability and thermal stability of Al-Ni-Zi-Y alloy. However with the increase of Cu element, the GFA and thermal stability reduce apparently. There are no Tg which is taken as the onset temperature of this endothermic signal can be observed since crystallization takes place first and there are pre-exist a-Al nucleus distract in amorphous. The effect of Cu in refining the size of the nano-crystals was attributed to enhance nucleation increasing the number density of the nano-crystals.It also can found Al85Ni8Zr3Cu2Y2 alloy and Al85Ni10Zr5 alloy can form nano-crystal a-Al embedded in amorphous structure by the means of quench at certain condition or heat treatment at initial crystal temperature for 30min.更多还原