Engineering Commons^™

Development Of An Aluminum Semi-Solid Extrusion Process, T Rattanochaikul, S Janudom, N Memongkol, J Wannasin

Journal of Metals, Materials and Minerals

Semi-solid extrusion process is a new forming process that is quite promising because the process requires lower forming pressure than conventional solid extrusion. In addition, semi-solid extrusion does not require large machines, which results in lower production costs. The aim of this article is to study the feasibility of an aluminum semi-solid extrusion process. The semi-solid technique selected for usage in this study was the Gas Induced Semi-Solid (GISS) process. The laboratory extrusion system was developed in this work. In the experiments, nitrogen gas was injected into aluminum melt for about 5 seconds. After that, the obtained semi-solid slurry was …

Deformation Study Of Nanocrystalline Ni-Fe Alloy Using Synchrotron Diffraction, Li Li

Doctoral Dissertations

This dissertation addresses two critical issues in the deformation of nc metals and alloys: (1) A stress-induced genuine grain growth after the plastic deformation rather than just a change of the grain shape; (2) A systematically quantitative study of micrsostructural evolution during the plastic deformation.

These two critical issues point to the deformation of nc materials with the average-grain sizes within the range of 10 to 50 nm, which is the most interesting and controversial region in the current time. The current study provides a systematic and detailed microstructural evolution for this region, which is definitely beneficial for the investigation …

Microstructure Modification Of Cu0.2ag2.8sbsete2 Through, Sloan Lindsey

All Theses

Cu0.2Ag2.8SbSeTe2 is new potential thermoelectric compound that exhibits very low thermal conductivity and a region of glass-like thermal conductivity. The compound phase segregates into AgSbTe2 and Ag2Te phases with Se and Cu acting as isoelectronic dopants. Backscatter SEM imaging is used to study the resulting microstructure. Normally cast samples exhibit cracks forming near the interfaces of the two phases. In this work we show that the cracks are caused by a low temperature monoclinic to cubic phase transition that occurs in the Ag2Te phase. We demonstrate that through rapid quenching we can control the size and shape of the phase …

An Investigation Of Microstructural Change Of Low Alloy Steel Aisi 4150 By Seebeck Coefficient, T Samran, P Termsuksawad

Journal of Metals, Materials and Minerals

Low alloyed steels, whose hardness can be modified by heat treatment, have been widely used in various applications. After heat treatment, they are normally destructively characterized and tested by many approaches via optical microscope and hardness testing. It is useful to develop a non-destructive method relating to its properties and microstructures. The proposed non-destructive approach in this study is the Seebeck coefficient measurement. The materials in this study were carbon steels AISI 4150 rod with a diameter of 1.3 cm and length of 3 cm. The specimens were heat-treated at 900ºC for 1 hour and were then cooled to room …

Microstructural Evolution Of Nickel During Spark Plasma Sintering, Matthew Thomas Luke

Boise State University Theses and Dissertations

Spark plasma sintering (SPS) is reported to produce materials with properties superior to those that result from conventional processing techniques. Spark plasma sintering is also reported to process materials at lower temperatures and in a shorter time than other processes, which may facilitate the synthesis of materials that are traditionally difficult to process. While the properties of materials that result from SPS processing have been studied, there is not a thorough understanding of the evolution of the microstructure in response to SPS process parameters. A comparison of the microstructure of nickel produced by SPS at varying ramp rate, temperature, dwell …