Research On High Content TiC Reinforced Aluminum Composite By TIG Melting

In order to obtain a material with high hardness and high wear resistance，akind of TiC，Al，Ti and graphite mixed powder is pressed into alloy blocks，thenprepare into a graphite crucible with TIG smelting for producing high TiC content(≥wt.50%) particles reinforced Al matrix composites in this subject．Combined withthe use of DSC，XRD，OM，SEM and EDAX analysis and other methods，thethermodynamics and kinetics of Al-Ti-C system in response to external TiC isstudied．Based on the analysis of the formation mechanisms and microstructuremorphology of TiC particle， some problems and process parameters affectingcomposites,property in TIG smelting is came up．Finally，the test results of hardnessand wear resistance is analysised．The research shows that the preparation process of high TiC content particlesreinforced Al matrix compositesin by TIG melting，when the temperature is low，TiCcan be produced by reaction between Al3Ti and the carbon atoms dissolved in the Almelt，or between Al4C3and titanium atom dissolved in the Al melt，and when thetemperature is high and raw milling time is longer，TiC can be generated not only bythat two methods，and also by [Ti] atoms and [C] atoms directly．So the reactionprocess in situ synthesis of TiC is extremely complex．When the temperature exceedsabout1300℃，intermediate such as Al4C3, Al3Ti completely disappeared．The results showed that sample with additional TiC， the Microscopicmorphology is a duplex structure that large additional TiC particles and situ small TiCparticles coexist，without additional TiC，TiC particles in Al matrix are relativelyuniform in size，but，the size of the situ TiC is larger than that of the sample withadditional TiC．Besides，additional TiC can inhibit violent exothermic reaction ofAl-Ti-C system，and has a role to reduce the holes and particles grow excessively inAl matrix．On the preparation process parameters，the most suitable current of TIG is150A，and the most appropriate duration of TIG smelting is15s，when in thisparameter，the reaction more complete，and more moderate TiC particle presented．Inthe constant current，compared to DC，in the process of AC in TIG melting，the total calories of sample in the whole process to get to be small，so the reaction ofAl-Ti-C system and the growth process of TiC particles lag some．In addition，the high content of TiC particles reinforced Al matrix compositeswith TIG melting can overcome the previous shortcomings of low TiC content (≤wt.30%) reinforced Al matrix composites that Al3Ti，Al4C3and other intermediateproducts is difficult to react completely．So，its hardness and wear resistance isgreatly improved．The hardness increased about7times higher than L1060aluminumalloy and about4times higher than20%TiCp/Al composites，and the wear resistanceincreased by4times compared to L1060aluminum alloy and increased by2timescompared to20%TiCp/Al composites．...