Demonstration of Ultrahigh-Strength Nanocrystalline Copper Alloys for Military Applications

................................................................................................................................. 1 Project Objective ................................................................................................................... 2 Background ............................................................................................................................ 2 Current Status of CuBe Alloys ......................................................................................... 2 Nanocrystalline Metals, A Suitable Alternative Replacement Material? ......................... 3 Theory on Stabilizing Nanocrystalline Metals for CuBe Replacement ............................ 5 Putting Theory into Practice, Creating a Stabilized Nanocrystaline Metal by High Energy Mechanical Alloying ............................................................................................ 5 High Energy Mechanical Alloying .............................................................................. 5 Advantages of Mechanical Alloying Over Other Processes ....................................... 5 The Production of Particulates ...................................................................... 5 Increased Solubility Limits .............................................................................. 5 Production of the Smallest Possible Grain Size .............................................. 5 Challenges with Consolidation of Nanocrystalline Materials .......................................... 6 Consolidation of Thermally Stable Powders .............................................................. 6 Pressure Assisted Sintering ......................................................................................... 7 Severe Plastic Deformation Processing ...................................................................... 7 Experimental Methods .......................................................................................................... 8 Downselection of Alloys ................................................................................................... 8 Laboratory Investigations: Small Powder Quantity .......................................................... 9 Laboratory Investigations: Transition from Small to Large Scale Powder Quantity ........ 9 Laboratory Investigations: Consolidation Methods ....................................................... 11 Equal Channel Angular Extrusion (ECAE) ............................................................. 11 Field Assisted Sintering Technology (FAST) ............................................................ 12 Characterization of Alloy Properties ............................................................................... 13 Vickers Hardness Testing ......................................................................................... 13 Compression Testing ................................................................................................. 14 Wear Testing ............................................................................................................ 14 Electrical and Thermal Conductivity Testing ........................................................... 14 Transmission Electron Microscopy (TEM) ............................................................... 14 Scanning Electron Microscopy (SEM) ..................................................................... 15 Differential Scanning Calorimetry Analysis (DSC) .................................................. 15 X-Ray Diffraction Studies ......................................................................................... 15 Atomic Simulations ................................................................................................... 15 Results ................................................................................................................................... 15 Experimental Results: Small Scale Samples ................................................................... 15 Experimental Results: Simulations ................................................................................. 19 Experimental Results: Mechanical Properties ................................................................ 22