The Effect of Segregation on Grain Boundary Fracture in Poly-Crystalline Alloys: Beneficial Versus Harmful Segregants

我们将研究通过少量杂质的存在来控制铁-锰、铂-铑-钨、铱和镍铝化物的延性或脆性的机制。这些合金代表了一系列的晶体结构，并将使人们能够测试观察到的效应的一般性。为了确定杂质对晶界阻碍滑移传输能力的影响，将对掺入延性杂质或脆化杂质的材料进行Hall-Petch实验。测量了表面和晶界的相对杂质偏析行为。透射电子显微镜中的原位变形将提供对滑移传输机制的详细了解。

The mechanisms that control the ductility or embrittlement in iron-manganese, platinum-rhodium-tungsten, iridium, and nickel aluminide by the presence of small amounts of impurities will be studied. These alloys represent a range of crystal structures and will allow one to test the generality of the observed effects. Hall-Petch experiments on materials doped with either ductilizing or embrittling impurities will be done to determine the effect of impurity on the ability of grain boundaries to impede the transmission of slip. Measurement of the relative impurity segregation behavior to surfaces and grain boundaries will be made. In situ deformation in TEM will provide a detailed understanding of the mechanisms involved in slip transmission.