Joseph Paras - Academia.edu (original) (raw)

Papers by Joseph Paras

The potential application of nanotechnology and advanced materials in both DoD weapons systems an... more The potential application of nanotechnology and advanced materials in both DoD weapons systems and commercial products is great. ARDEC is exploring a wide variety of materials and technologies to solve current technology gaps. Addressing these gaps will enhance lethality and survivability of the Warfigher. ARDEC is combining internal capabilities with those of key industry and academic partners to address these gaps. This talk will describe some of the recent research and successes under a variety of efforts. Nanocomposite superthermites, the replacement of single-point failure materials, the use of nanoporous silicon as an alternative to nano-aluminum and near-term and mid-term goals to develop new materials for the Energetics, Reactive Materials, Armor/Anti-armor and Power & Energy product areas will be discussed.

ARDEC is exploring the use of reactive materials, and structural reactive materials, in various a... more ARDEC is exploring the use of reactive materials, and structural reactive materials, in various applications such as the replacement of warhead components, particle impact mitigation sleeves (PIMS liners), reactive fragments, and reactive casings. In order for these materials to be developed and transitioned effectively, the proper processing, characterization, and handling techniques and precautions need to be established. Effectively identifying all of these issues will ensure that we will see heavier usage of these materials in the near future to enhance the performance of munitions and to improve muntions' response to outside stimuli such as bullet impact (BI), fragment impact (FI) and cookoff. Achieving Insensitive Munitions (IM) compliance is a key goal while not reducing the overall effectiveness of the warhead. This paper will discuss some of the materials and techniques ARDEC has explored in order to build the necessary capability to handle these types of materials, as ...

Scripta Materialia, 2011

The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composit... more The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composites was studied. Al 5083 (Al-4.5 Mg-0.57Mn-0.25Fe) composites, with grain size of 115 nm and B 4 C reinforcement size of 38 nm, were fabricated via cryomilling and consolidation. The result reveals that the presence of nanoparticles enhances strength by interacting with dislocations, while simultaneously retarding grain growth. Furthermore, the nanoparticles-reinforced composite exhibits enhanced plasticity relative to the same material reinforced with micrometric particles. The underlying mechanisms are discussed.

Metallurgical and Materials Transactions A, 2013

ABSTRACT The influence of tooling material, i.e., graphite and WC-Co, on the microstructure of a ... more ABSTRACT The influence of tooling material, i.e., graphite and WC-Co, on the microstructure of a spark plasma sintering (SPS) consolidated, nanostructured aluminum alloy is studied in this paper. The results show that tooling selection influences microstructure evolution, independent of process parameters. The influence of tooling on microstructure is rationalized on the basis of the following factors: heating rate, electrical current density, localized heating, and imposed pressure. A theoretic framework, based on the physical properties of graphite and WC-Co, is formulated to explain the observed behavior.

Materials Science and Engineering: A, 2011

Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostati... more Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

SUMMARY: Powder Production Capability--Able to produce nanostructured materials with enhanced pro... more SUMMARY: Powder Production Capability--Able to produce nanostructured materials with enhanced properties using high energy milling--Able to produce almost any nano scale powder at a rate up to 1kg/hr for potential applications involving anti-corrosion ...

Metallurgical and Materials Transactions A, 2012

Aluminum alloys are widely used because they are lightweight and exhibit high strength. In recent... more Aluminum alloys are widely used because they are lightweight and exhibit high strength. In recent years, spark plasma sintering (SPS) technology has emerged as a viable approach to sinter materials due to its application of rapid heating and high pressure. In this study, SPS was chosen to consolidate dense ultrafine-grained (UFG) bulk samples using cryomilled nanostructured Al 5083 alloy (Al-4.5Mg-0.57Mn-0.25Fe, wt pct) powder. Both bimodal microstructure and banded structure were observed through transmission electron microscopy (TEM) investigation. The evolution of such microstructures can be attributed to the starting powder and the process conditions, which are associated with the thermal, electrical, and pressure fields present during SPS. A finite element method (FEM) was also applied to investigate distributions in temperature, current, and stress between metallic powder particles. The FEM results reveal that the localized heating, deformation, and thermal activation occurring at interparticle regions are associated with the formation of the special microstructure.

The potential application of nanotechnology and advanced materials in both DoD weapons systems an... more The potential application of nanotechnology and advanced materials in both DoD weapons systems and commercial products is great. ARDEC is exploring a wide variety of materials and technologies to solve current technology gaps. Addressing these gaps will enhance lethality and survivability of the Warfigher. ARDEC is combining internal capabilities with those of key industry and academic partners to address these gaps. This talk will describe some of the recent research and successes under a variety of efforts. Nanocomposite superthermites, the replacement of single-point failure materials, the use of nanoporous silicon as an alternative to nano-aluminum and near-term and mid-term goals to develop new materials for the Energetics, Reactive Materials, Armor/Anti-armor and Power & Energy product areas will be discussed.

ARDEC is exploring the use of reactive materials, and structural reactive materials, in various a... more ARDEC is exploring the use of reactive materials, and structural reactive materials, in various applications such as the replacement of warhead components, particle impact mitigation sleeves (PIMS liners), reactive fragments, and reactive casings. In order for these materials to be developed and transitioned effectively, the proper processing, characterization, and handling techniques and precautions need to be established. Effectively identifying all of these issues will ensure that we will see heavier usage of these materials in the near future to enhance the performance of munitions and to improve muntions' response to outside stimuli such as bullet impact (BI), fragment impact (FI) and cookoff. Achieving Insensitive Munitions (IM) compliance is a key goal while not reducing the overall effectiveness of the warhead. This paper will discuss some of the materials and techniques ARDEC has explored in order to build the necessary capability to handle these types of materials, as ...

Scripta Materialia, 2011

The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composit... more The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composites was studied. Al 5083 (Al-4.5 Mg-0.57Mn-0.25Fe) composites, with grain size of 115 nm and B 4 C reinforcement size of 38 nm, were fabricated via cryomilling and consolidation. The result reveals that the presence of nanoparticles enhances strength by interacting with dislocations, while simultaneously retarding grain growth. Furthermore, the nanoparticles-reinforced composite exhibits enhanced plasticity relative to the same material reinforced with micrometric particles. The underlying mechanisms are discussed.

Metallurgical and Materials Transactions A, 2013

ABSTRACT The influence of tooling material, i.e., graphite and WC-Co, on the microstructure of a ... more ABSTRACT The influence of tooling material, i.e., graphite and WC-Co, on the microstructure of a spark plasma sintering (SPS) consolidated, nanostructured aluminum alloy is studied in this paper. The results show that tooling selection influences microstructure evolution, independent of process parameters. The influence of tooling on microstructure is rationalized on the basis of the following factors: heating rate, electrical current density, localized heating, and imposed pressure. A theoretic framework, based on the physical properties of graphite and WC-Co, is formulated to explain the observed behavior.

Materials Science and Engineering: A, 2011

Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostati... more Composites of graphene platelets and powdered aluminum were made using ball milling, hot isostatic pressing and extrusion. The mechanical properties and microstructure were studied using hardness and tensile tests, as well as electron microscopy, X-ray diffraction and differential scanning calorimetry. Compared to the pure aluminum and multi-walled carbon nanotube composites, the graphene-aluminum composite showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler.

SUMMARY: Powder Production Capability--Able to produce nanostructured materials with enhanced pro... more SUMMARY: Powder Production Capability--Able to produce nanostructured materials with enhanced properties using high energy milling--Able to produce almost any nano scale powder at a rate up to 1kg/hr for potential applications involving anti-corrosion ...

Metallurgical and Materials Transactions A, 2012

Aluminum alloys are widely used because they are lightweight and exhibit high strength. In recent... more Aluminum alloys are widely used because they are lightweight and exhibit high strength. In recent years, spark plasma sintering (SPS) technology has emerged as a viable approach to sinter materials due to its application of rapid heating and high pressure. In this study, SPS was chosen to consolidate dense ultrafine-grained (UFG) bulk samples using cryomilled nanostructured Al 5083 alloy (Al-4.5Mg-0.57Mn-0.25Fe, wt pct) powder. Both bimodal microstructure and banded structure were observed through transmission electron microscopy (TEM) investigation. The evolution of such microstructures can be attributed to the starting powder and the process conditions, which are associated with the thermal, electrical, and pressure fields present during SPS. A finite element method (FEM) was also applied to investigate distributions in temperature, current, and stress between metallic powder particles. The FEM results reveal that the localized heating, deformation, and thermal activation occurring at interparticle regions are associated with the formation of the special microstructure.