Powder Alloying & Spheroidization^SM

Powder Alloying & Spheroidization Technical Paper

PAS also creates alloys from two or more materials by combining powder particles in the molten state. Spherical, metallurgically alloyed particles form upon solidification. In contrast to traditional blended powders where each elemental particle has a unique shape and size, PAS produces spherical particles regardless of their composition. Each PAS™ sphere contains some of each element as illustrated below:

W-Re Blended Powder Before and After PAS Figure 1: W-Re blended powder before Figure 2: W-Re blended powder after PAS Enhanced Flow Characteristics PAS increases flow as evidenced by Hall Flow Test results on non-PAS and PAS-processed powders per ASTM B 213. This test measures the time necessary for a given amount of powder to pass through a critical orifice as result of gravity. Hall Flow Test Results Composition Flow (g/s) Non-PAS PAS W No flow 100g/10s W-25Re No flow 100g/10s W-2Re No flow 100g/11s Mo No flow 20g/20s Mo-40Re No flow 100g/15s Ta No flow 110g/10s Note that powders tested prior to PAS resulted in no flow, (i.e. failure of the test) translating to inconsistent powder flow. In contrast, all PAS powders passed the flow test, demonstrating excellent flow. Applications PAS powders are suited for a variety of process applications including: Powder Metallurgy Rapid Prototyping Thermal Spraying Laser Cladding Metal Injection Molding Automotive Coatings Hardfacing Piezoelectric devices Medical Applications

• Spherical Particle Shapes
• High Density
• Improved Flow
• Low Oxygen Content
• Controlled Particle Size Distribution

Tungsten Crystalline Powder Before and After PAS

Figure 1: SEM backscattered image of tungsten crystalline powder with blocky, faceted powder particles.
Figure 2: SEM backscattered image of PAS tungsten powder. Highly spherical particles are produced.

Spray-dried Molybdenum Powder Before and After PAS

Figure 1: SEM backscattered image of spray-dried Mo powder. Each particle is comprised of smaller (<10 um diamter) agglomerated particles.
Figure 2: SEM backscattered image of PAS Mo powder. The agglomerated particles of feedstock have been convered to solid Mo particles, reducing overall surface area and O₂ content.

PAS Material Feedstock

Chemical Analysis

Trace Element Chemical Analysis Of Mo-40Re Powder
Element	Before PAS	After PAS
C	82	53
O	13000	400
Al	100.0	35.0
Si	145.0	42.0
P	13.0	6.2
Ca	124.0	27.0
Ti	34.0	6.8
Cr	70.0	19.0
Fe	490.0	265.0
Ni	50.0	24.0
Ta	600.0	<5
Mg	9.3	<5
Mn	11	<5
Cu	12	<5
Zr	59	<5
Ba	<10	<5
All values expressed in ppmw.