Hydrogen-Induced Lattice Rearrangements in Alloys

点击翻译按钮获取中文摘要

This research explores the effects of absorbed hydrogen atoms on phase changes in metal alloys. Dissolved hydrogen appears to enhance metal atom mobility and allows phase separation not normally observed at lower temperatures. Hydrogen-induced lattice mobility, (HILM) is, therefore, the subject of this program. Using the palladium-rhodium alloy system as a model, phase boundary compositions are determined as a function of hydrogen content. Hydrogen is introduced under high pressures (up to 2000 atmospheres). Phase segregation studies incorporating HILM are extended to the palladium-platinum and nickel-copper alloy systems. HILM-induced ordering of intermetallic phases is examined in selected intermetallics in these alloy systems. Analytical techniques such as electron microprobe analysis and scanning transmission electron microscopy are employed to characterize the phases and related changes that occur. Mechanisms of HILM are considered based on the experimental data developed. %%% Results from this research should clarify how HILM can be used effectively in such areas as phase diagram determination, materials synthesis, and micro-alloying.