Mechanisms Behind The Indium Whisker Gtowth On Ti₂InC

The MAX phase is a type of layered carbide or nitride.The unique crystal structure makes it have the excellent properties of metal and ceramics,and has broad application prospects.However,the growth of A element whiskers makes people question the stability of the MAX phase structure and its reliability during service.This topic takes Ti₂InC as the research object,and studies the growth mechanism of indium whiskers on the Ti₂InC surface from the atomic source and driving force of the whisker growth.The main research contents and results are as follows:Ti₂InC powder was synthesized starting from elemental Ti/In/C powder mixtures by pressureless sintering.By optimizing sintering parameters and raw material components,Ti₂InC phase with a purity of 94 wt.%was synthesized.The synthesis mechanism and route of Ti₂InC were discussed by means of thermal analysis and phase characterization.The indium whisker can grow on Ti₂InC at room environment,and the surface is covered with a very thin polycrystalline oxide layer.The indium whisker has the similar morphological characteristics to metal whiskers grown in other systems such as alloy coatings.The apparent density,indium content and culture environment of Ti₂InC/In samples significantly affect the growth of indium whisker.The growth trend of indium whisker increases with the increase of the apparent density of the sample,and with the increase of indium content,the growth trend of indium whisker first strengthened and then weakened.At 100°C,the growth trend of indium whisker is the most obvious,while at the same cultivation temperature,the growth trend of whiskers tends to weaken with the increase of humidity.Under the same temperature and humidity,the growth trend of whisker in air atmosphere is obviously stronger than that in Ar atmosphere.Compared with Ti C/In and Si C/In systems,the driving effect of interface energy on the growth of whiskers was studied.Compared with Ti C/In and Si C/In samples,Ti₂InC phase in Ti₂InC/In samples has low hardness and is easy to fracture during ball milling,forming more Ti₂InC-In interfaces,which provides more driving force for whisker growth.The difference in the trend of whisker growth and the thermal analysis curve proved the rationality of the interface energy to drive the growth of the whiskers.By cross experiments of Ti₂InC/A and Ti₂AC/In（A=Al,Sn）,the element source of indium whisker growth on Ti₂InC/In was studied.In Ti₂InC/A and Ti₂AC/In systems,when the interaction between indium-A is weak,the element source for whisker growth is mainly provided by the elementary substance in the system.When the indium-A interaction is strong,the source of the whisker growth elements is provided by the elementary substance and the plane A of MAX phase dissociation.