how can i display my posts alphabetically?

Question

Add both orderby and order query parameters.

Here is an excerpt of the PHP code you need:

$query_args = array(
    "category_name" => "elektrotechniek",
    "orderby" => "post_title",
    "order" => "ASC"
);

Use post_title in case you need to order your posts by title, or post_namein case you prefer to order your posts by slug. Any other field of the wp_posts table can be used to order the posts by.

If you don’t add ASC as the order value, WordPress orders the posts in a descendant way.