New tungsten alloy has high strength at elevated temperatures

Tungsten-hafnium-carbon alloy has tensile strengths of 88,200 psi at 3000 deg F and 62,500 psi at 3500 deg F. Possible industrial applications for this alloy would include electrical components such as switches and spark plugs, die materials for die casting steels, and heating elements

Processing of ultrafine-size particulate metal matrix composites by advanced shear technology

Copyright @ 2009 ASM International. This paper was published in Metallurgical & Materials Transactions A 40A(3) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.Lack of efficient mixing technology to achieve a uniform distribution of fine-size reinforcement within the matrix and the high cost of producing components have hindered the widespread adaptation of particulate metal matrix composites (PMMCs) for engineering applications. A new rheo-processing method, the melt-conditioning high-pressure die-cast (MC-HPDC) process, has been developed for manufacturing near-net-shape components of high integrity. The MC-HPDC process adapts the well-established high shear dispersive mixing action of a twin-screw mechanism to the task of overcoming the cohesive force of the agglomerates under a high shear rate and high intensity of turbulence. This is followed by direct shaping of the slurry into near-net-shape components using an existing cold-chamber die-casting process. The results indicate that the MC-HPDC samples have a uniform distribution of ultrafine-sized SiC particles throughout the entire sample in the as-cast condition. Compared to those produced by conventional high-pressure die casting (HPDC), MC-HPDC samples have a much improved tensile strength and ductility.EP-SR

Work Organisation and Innovation - Case Study: FAVI, France

[Excerpt] FAVI is an SME based in Hallencourt in the Somme, a département in the Picardy region of France. It is a pressure die-casting company specialising in copper alloys that currently employs 406 people. The company designs, optimises, smelts, machines and assembles copper alloy pieces. Interns can at times account for 10% of the workforce. Founded in 1957, this société anonyme (public limited company) with a capital of €960,000, is part of the AFICA Group, which purchased FAVI in 1971

Rheo-diecasting AZ91D magnesium alloy

Magnesium recycling has become more important in today’s environmentally aware society. To prompt the usage of recycled magnesium scrap and further improve casting structure and properties, a novel physical approach, the rheo-diecasting process (RDC), has been applied in the present study to deal with AZ91D Mg-alloy directly from die-casting scrap. The experimental results show that the RDC process can be used to produce recycled AZ91D alloy with fine and uniform microstructure and a very low level of porosity. The intermetallic compounds containing the impurity elements were of fine and of spherical morphology, distributed uniformly in the alloy matrix. No oxide particle clusters or oxide films were found in the RDC microstructure. The tensile properties of the recycled AZ91D alloy were comparable to those produced by RDC from the primary alloy ingots., and much better than those produced by conventional High Pressure Die Casting (HPDC)

Finite Volume Simulation Framework for Die Casting with Uncertainty Quantification

The present paper describes the development of a novel and comprehensive computational framework to simulate solidification problems in materials processing, specifically casting processes. Heat transfer, solidification and fluid flow due to natural convection are modeled. Empirical relations are used to estimate the microstructure parameters and mechanical properties. The fractional step algorithm is modified to deal with the numerical aspects of solidification by suitably altering the coefficients in the discretized equation to simulate selectively only in the liquid and mushy zones. This brings significant computational speed up as the simulation proceeds. Complex domains are represented by unstructured hexahedral elements. The algebraic multigrid method, blended with a Krylov subspace solver is used to accelerate convergence. State of the art uncertainty quantification technique is included in the framework to incorporate the effects of stochastic variations in the input parameters. Rigorous validation is presented using published experimental results of a solidification problem

Water-soluble cores – verifying development trends

Application of pure inorganic salt-based cores has been known since the end of the 20th century, especially in the field of gravity and low-pressure die casting. The contemporary trend in technology leads to the use of the cores in the field of non-ferrous-alloy high-pressure die casting. The main methods of the core production include high-pressure squeezing and shooting (warm core box). During research processes it was shown that pure-salt application is not very suitable for high-pressure casting. That is why a composite salt-based matrix of defined properties was started to be used. The aim of the paper is to verify the influences of the chemical composition, shape and morphology of the grains of various NaCl compounds on the mechanical properties (the bending strength) of water-soluble salt cores used for Al-alloy high-pressure die casting and to evaluate their properties resulting from the squeezing and shooting methods.Web of Science491676