Pinch-off of dendrite arms as a result of this effect has therefore been synonymous with fragmentation for the last few decades. All known fragmentation mechanisms are based on shape instability that is caused by the curvature effect (the capillary effect). Radiography of the solidification in metallic alloys has shown that fragmentation that is caused by local solute enrichment can occur spontaneously in the mushy region 9, 10, 11, 12, 13, 14. Depending on the configuration of the dendrite arms and the temperature distribution, melt flow in the mushy region can cause local solute enrichment around the necks of dendrite arms and promotes fragmentation. Another contributing mechanism is local solute enrichment, which is caused by melt flow in the mushy region 1, 9, 10, 11, 12, 13, 14. Thus, dendrites have inherent shape instabilities that are driven by the solid–liquid interfacial energy these are essentially the same as Plateau–Rayleigh instabilities. Both factors originate from shape instabilities that are associated with the dendritic geometries. Another is remelting of dendrite arms after recalescence during solidification from an undercooled melt 7, 8. One is remelting at the dendrite arm necks during coarsening between developing arms 1, 2, 3, 4, 5, 6. Several factors can initiate dendrite arm fragmentation. The detachment of fragmented dendrite arms is one mechanism that promotes the transition from a columnar to an equiaxed structure. The results show a massive-like transformation inducing the dendrite arm fragmentation has a role in formation of the solidification structure and the austenite grain structures in the Fe–C alloys.Īn understanding of the morphological transition from columnar to equiaxed structures during the solidification of metallic alloys is fundamental to control the microstructures and grain structures of cast products. In unidirectional solidification, a slight increase in temperature moves the ferrite–austenite interface backwards and promotes detachment of the primary and secondary arms at the δ–γ interface via a reverse peritectic reaction. The austenite grains are fragmented by the liquid phase that is produced at the grain boundary. The transformation produces refined austenite grains and ferrite–austenite boundaries in dendrite arms. A massive-like transformation from ferrite to austenite rather than the peritectic reaction occurs during or after ferrite solidification. Here we report a dendrite arm fragmentation mechanism. Time-resolved and in situ imaging using synchrotron radiation X-rays allows the observation of dendrite arm fragmentation in Fe–C alloys. Send us feedback.Dendrite arm fragmentation is considered in solidification structure tailoring. These example sentences are selected automatically from various online news sources to reflect current usage of the word 'dendrite.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. 2020 Many of the fatal flaws in lithium are related to the same dendrite problem.Ĭaroline Delbert, Popular Mechanics, 4 Mar.
2020 Duller, shallower dendrites don’t pierce the battery and cause fires.Ĭaroline Delbert, Popular Mechanics, 4 Mar. Douglas Fields, Scientific American, 12 Mar. 2021 Vascular changes and the sprouting and pruning of axons and dendrites that extend from the main body of a neuron could also do the same. Leslie Nemo, Scientific American, 11 Feb. University Of Houston Energy Fellows, Forbes, 14 June 2021 Making the battery out of mostly solid materials helps prevent dendrite formation in more than one way.Ĭaroline Delbert, Popular Mechanics, Plate snowflake that turned into a stellar dendrite. 2022 This build-up, known as lithium dendrite, can short-circuit the battery and shorten its life. Karen Hopkin, Scientific American, 30 June 2022 Sometimes, those reactions form a pesky thing called a dendrite-a vein of material in the electrolyte that gradually extends and may eventually connect the anode and the cathode, causing a short-circuit-and a fire. Recent Examples on the Web That dendrite collects the incoming electrical signals and sends them to a capacitor which…like a neuronal cell body…integrates the information.
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