【作者】 杨殿伟；

【导师】 曹福洋；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2009， 硕士

【摘要】 本文以喷射成形Al-Zn-Mg-Cu系超高强铝合金为对象,研究了热处理对合金组织和性能的影响。经研究发现,固溶温度对合金的组织和性能影响较大,采用双级固溶470℃×2h+490℃×1h可以保证不发生过烧前提下,最大程度使合金中的各种析出相回溶,最后的到合金的最优化热处理工艺。合金的析出行为与时效硬化和电导率特性具有一定的对应关系,因此有必要对合金的时效硬化和电导率特性经行研究。针对单级时效硬化特性的研究发现,喷射成形Al-Zn-Mg-Cu系超高强铝合金时效硬化具有双峰的特点,峰时效时间为19h左右,与之对应的合金的最高强度为800MPa左右。相比之下,双级时效合金的强度下降了8%左右。利用Starink模型对合金的电导率进行研究,发现合金的电导率与时效时间、时效温度和溶解到基体中的合金元素的数量有关,时效时间越长,时效温度越高,合金的电导率越高,溶解到集体中合金元素量越多,溶解的合金元素种类越多,合金的电导率越低。用透射电镜对合金的析出特性研究发现,单级时效达到峰时效后,晶内析出的沉淀相呈细小的球状,比较规则,尺寸在几nm左右,弥散分布在晶粒内部。经过对选区电子衍射花样及X射线衍射谱的标定,确认晶内沉淀相为η’相X ray diffraction - XRD也证明了这一相,随着时间的延长η’逐渐长大粗化,并向η相转变。双级时效时,随着时间的延长,沉淀相遵循—GP区→η’过渡相（MgZn）→η（MgZn₂）稳定相这一转化规律。喷射成形高强铝合金的断裂方式为韧性断裂,部分韧窝中可看到第二相颗粒。峰时效拉伸断口形成大量的韧窝,过时效随着时间的延长,合金的断裂方式由韧窝断裂向穿晶断裂转变,合金的塑性逐渐降低。更多还原

【Abstract】 In this paper, we studied the effect of heat treatment on the microstructure and properties of the spray forming Al-Zn-Mg-Cu ultra-high strength aluminum alloy. Results show that solid solution temperature had an important effect on the alloy performance of the organization, two-step solid solution using 470℃×2h +490℃×1h to ensure that burning does not happen under the premise of the greatest extent variety of alloy precipitates back dissolved, at last we get the final optimization of the alloy heat treatment process.Alloy age-hardening and precipitation behavior and electrical conductivity properties have a certain relationship, it is essential to study the age-hardening alloy properties and electrical conductivity. By the study of single-stage age-hardening characteristics of the found that spray forming Al-Zn-Mg-Cu Department of ultra high strength aluminum alloy with a bimodal age-hardening characteristics, peak aging time for the 19h, which corresponds to the maximum strength of alloys of about 800MPa. In contrast, Two-step aging treatment of alloy decreased the intensity of about 8%. Starink model using the conductivity of the alloy to study and found that the conductivity of alloys related with aging time, aging temperature and dissolved into the matrix of the number of alloying elements, and spent a longer time, the higher the aging temperature, the higher the conductivity alloy had ,and vice versa.By transmission electron microscopy-TEM study of precipitation characteristics, single-stage aging after reaching peak aging, the precipitation of intragranular precipitates were small spherical, more rules, the size at about few nm, the internal diffusion in the grain. After the demarcation of selected area electron diffraction pattern, we think that this phase ofη’, X ray diffraction - XRD has proved that this phase. With the time,η’ coarsening, gradually grew to theηphase. Two-step aging treatment, as time lengthens, the precipitation follow this GP→η’phase (MgZn)→ηThe way of ductile of spray forming of high strength aluminum alloy belongs to dimple fracture, and some second phase particles can be seen in the dimples. Peak ageing time formed a lot for dimples at the tensile fracture. with the extension of the time of two-step aging treatment, the way of ductile change into transcrystalline fracture and the plastic of alloy become lower.更多还原