ADDITIVE MANUFACTURING AM ALSO KNOWN AS 3D PRINTING IS POTENTIALLY A LOW COST AND ACCELERATED WAY OF MANUFACTURING CERTAIN COMPLEX METALLIC COMPONENTS BY ADDING SUCCESSIVELY LAYERS OF ALLOYS DIRECTLY CONTROLLED BY A 3D COMPUTER-AIDED DESIGN DATASET. IT HAS MANY CRITICAL APPLICATIONS IN NASA MISSIONS SUCH AS THOSE FOUND IN PROPULSION AND SPACECRAFT. PRIOR TO ACCEPTANCE OF AM PROCESSES BY NASA OTHER GOVERNMENT AGENCY AND COMMERCIAL SPACE MISSIONS HOWEVER A LONGSTANDING TECHNICAL CHALLENGE IS THE QUALIFICATION AND CERTIFICATION OF AM PROCESSES AND SYSTEMS FOR CRITICAL HIGH VALUE METALLIC COMPONENTS. THE MAIN OBJECTIVE OF THE PROPOSED RESEARCH IS TO DEVELOP A PHYSICS BASED PREDICTIVE MODELING APPROACH FOR A RIGOROUS YET COST EFFECTIVE WAY OF CERTIFICATION OF AM PROCESSING PARAMETERS ALLOY COMPOSITION AND RESULTING MICROSTRUCTURES FOR THE DESIRED PROPERTIES OF METALLIC COMPONENTS VIA LASER POWDER BED FUSION L-PBF PROCESS. THE PROPOSED RESEARCH WILL INTEGRATE TWO PHYSICS BASED PREDICTIVE MODELS ONE FOR MOLTEN POOL FLUID DYNAMICS AND THE OTHER FOR MICROSTRUCTURE EVOLUTION FOR L PBF OF INCONEL 718 OR IN718. FIRST OF ALL A NEW MOLTEN POOL MODEL CAPABLE OF SIMULATING MULTIPLE LASER PASSES ESPECIALLY THE EVOLUTION OF DEFECTS SUCH AS VOIDS AND A GENERALIZED CALPHAD PLUS PHASE FIELD MICROSTRUCTURE MODELING FRAMEWORK THAT INTEGRATES PROCESSING VARIABLES ALLOY COMPOSITION AND THE RESULTING HIERARCHICAL MICROSTRUCTURE WILL BE DEVELOPED. HIGH PERFORMANCE COMPUTING CLUSTERS WILL BE UTILIZED TO SPEED UP THE SIMULATIONS. THEN THE SIMULATION PREDICTIONS WILL BE VALIDATED BASED ON MOLTEN POOL BOUNDARIES AND MICROSTRUCTURE OF IN718 SAMPLES FABRICATED BY THE L PBF PROCESS AND CHARACTERIZED BY OPTICAL AND ELECTRON MICROSCOPY AS WELL AS HIGH-RESOLUTION X RAY TOMOGRAPHY. THIS INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING ICME APPROACH WILL ESTABLISH A FUNCTIONAL RELATIONSHIP BETWEEN BOTH THE MATERIAL COMPOSITION AND THE AM PROCESSING PARAMETERS AND RESULTING MICROSTRUCTURE. THIS NEW ICME APPROACH WITH SIGNIFICANTLY NEW CAPABILITIES FOR MULTIPLE LASER PASSES AND HIGHLY NON-LINEAR TIME TEMPERATURE PROFILES WILL IMPROVE DRASTICALLY THE RELEVANCE OF PROCESS MICROSTRUCTURE MODELING TO ACTUAL AM PRODUCTION PROCESSES. WHEN FULLY DEVELOPED IT WILL LAY THE FOUNDATION FOR PREDICTIVE MODELING BASED APPROACHES TO CERTIFY BOTH THE L PBF AND ALLIED AM PROCESSES AS WELL AS THE RESULTING AM MANUFACTURED FLIGHT HARDWARE ALLOWING FOR THE FULL REALIZATION OF THE BENEFITS OF AM IN MISSION CRITICAL AEROSPACE APPLICATIONS. MOREOVER ALTHOUGH DEMONSTRATED FOR IN718 THE INTEGRATED MODELING APPROACH CAN BE EXTENDED TO OTHER NASA MATERIAL SYSTEMS POTENTIALLY LEADING TO DRAMATIC IMPROVEMENTS IN PREDICTIVE MODELING BASED APPROACHES TO CERTIFY VARIOUS AM PROCESSES. HENCE THE PROPOSED RESEARCH IS HIGHLY RELEVANT TO THE SPECIFIC ESI APPENDIX GOALS AND OBJECTIVES.