稀土金属与铁和砷在高温的交互作用规律研究

The arsenic is a harmful impurity in steel. The strength and plasticity of steel can be significantly reduced by the arsenic that is liable to inclined to the crystal interfaces.There are still no any effective technique or methods to control or get rid of low melting point element arsenic during steelmaking. The low melting point element arsenic can turn into high melting point compounds with rare earth elements. The recent studies show that the rare earth elements may form high melting point compounds reacted with both low melting point element arsenic and iron. A certain amount of rare earth metals (chemically pure) and low melting point arsenic (analytical grade) with different atomic ratio from 1 to 5 are planned to be closed in the barrel-shaped cylinder machined by H08 steel, heated to 1073K-1273K for long enough time, and the interaction products among the cerium, arsenic and iron at high temperature will be determined by X-ray diffraction, metalloscope, and electronic probe microanalysis to know the microstructure, the phase composition and the phase structure, and the relative volume for various compounds. The developed conditions and the chemical stability of the ternary compound, the effect of the relative volume of the binary compound on the ternary compound developing, and the effect of both the temperature and the atomic ratio on the relative volume of various compounds will be studied. The developing conditions of both the binary compounds and the ternary compounds among the rare earth metals, iron, and arsenic at high temperature would be discovered. The interaction relationship among rare earth metals, iron, and arsenic at high temperature may be developed.

砷是钢中的有害杂质，多在晶界发生偏聚，可显著降低钢的强塑性。在炼钢过程中尚无有效去除及控制低熔点元素砷的可行方法与工艺。稀土元素与元素砷可生成稳定的高熔点化合物。近期研究表明，稀土元素与砷和铁可生成稳定的高熔点三元化合物。拟将一定量的稀土金属(化学纯)和低熔点砷(分析纯)按1-5的不同克原子比密封在特制的H08钢缸体内，加热至1073K-1273K的不同温度，保温一定的时间，应用XRD、扫描电镜、金相显微镜和电子探针微区分析等方法，分析测定不同实验条件下高温作用产物的组织结构、相组成、相结构、化合物种类以及相对生成数量；研究三元化合物的生成条件与化学稳定性、二元化合物的种类与相对生成数量对生成三元化合物的影响、温度和克原子比对各种化合物的生成与相对生成数量的影响；建立稀土金属与铁和砷在高温生成各种二元化合物与三元化合物的规律，建立稀土金属与铁和砷在高温的交互作用规律。

砷是钢中的有害杂质，多在晶界发生偏聚，可显著降低钢的强塑性。在炼钢过程中尚无有效去除及控制低熔点元素砷的可行方法与工艺。研究表明，稀土元素与砷和铁可生成稳定的高熔点三元化合物。将一定量的稀土金属(化学纯)和低熔点砷(分析纯)按1-5的不同克原子比密封在特制的工业纯铁（H08钢）缸体内，加热至1173K-1273K的不同温度，保温一定的时间，应用XRD、扫描电镜、金相显微镜和电子探针微区分析等方法，按计划实验研究了Fe-Ce-As交互作用产物的组织结构、相组成、相结构、化合物种类与相对生成数量，研究了温度、克原子比与生成化合物及其相对数量之间的关系；研究了稀土化合物的化学稳定性；研究了稀土金属铈与铁和砷之间的交互作用规律。铈-铁-砷三元系高温生成的化合物主要为Ce12Fe57.5As41、CeAs和Fe2As与α-Fe的混合物。镧-铁-砷三元系高温生成的化合物主要为La12Fe57.5As41、LaAs和Fe2As与α-Fe的混合物。钕-铁-砷三元系高温生成的化合物主要为NdAs和Fe2As与α-Fe的混合物；以及少量NdFeAs三元化合物。镨-铁-砷三元系高温生成的化合物主要为PrAs和Fe2As与α-Fe的混合物；可能有PrFeAs三元化合物。试样中稀土金属铈镧钕镨的单质与二元化合物在制样过程中可发生氧化与剥落，在干燥器中可延缓氧化剥落速度；铈镧钕镨的三元化合物在干燥器中稳定。